I think there are a few things to unpack here:
- possibility to pay by cash
- possibility to pay the driver
While London phased out cash payment of fares to the driver in 2014, paying cash was already disadvantageous for a number of years prior to that, because the cash fare had been steadily increased until it was nearly double the Oyster fare.
But even after that, it was not difficult to pay by cash if you wanted to - you just had to do it in advance. Oyster cards were still widely available for cash in many locations around the city, and the deposit was refundable. However, today, if you do not have an Oyster card already, you will need to buy one for a non-refundable £10. This is a significant barrier to paying by cash.
Unlike some other smartcard systems which have large minimum topups, Oysters can be topped up in 5p increments (10p at TfL machines). These sorts of issues can be found in other public transport systems too. Sometimes only a selection of possible fares can be paid by cash and/or bought from the driver, and sometimes it is more expensive to pay by cash versus other payment methods.
TURKIYE - Istanbul - when I visited in 2016, it was not possible to buy tickets on board. All bus passengers had to use an Istanbulkart or a prepaid token. Cash appeared to be the only payment method accepted to buy an Istanbulkart at that time. I could not figure out how to access the prepaid token system.
I have been unable to find out when the sale of cash tickets on board Istanbul buses was phased out. It could well have been earlier than London in 2014.
BOSNIA - Sarajevo - tickets can be bought using cash at many convenience kiosks around the city, as well as at offices at some bus terminals. Non-cash payments are not always available. One ticket kiosk refused a sale and told me to purchase on board the bus, but I never saw anyone buying on board. I went to another kiosk 20m away who sold me a ticket.
CROATIA - Zagreb - cash is accepted on board but it costs around 1.5x more than buying tickets from convenience kiosks. However, it appears that the daily ticket of €3.98 is the same price on board and in advance.
GERMANY - I have not come across a bus which did not accept cash on board, however many people use the EUR58 monthly subscription ticket. It appears to be impossible to buy this ticket with cash, although I recall a forum post about a successful cash purchase when the ticket was first introduced.
GUERNSEY - when I visited in 2023, it was possible to buy a pre-loaded Puffin smartcard for GBP/GGP8 by cash or card at the airport, but shop opening hours were limited. It was not possible to check the status of the smartcard at the airport. The £8 comprised a £3 non-refundable card fee and £5 of credit. Contactless payments were accepted on board, for a higher fare than using Puffin. The Puffin smartcard could be topped up using cash at the main bus terminal in St Peter Port (limited opening hours). I observed Scottish, N.Irish and Jersey currency being accepted there.
HONG KONG - all buses accept cash on board. Fares are the same for cash and non-cash, except that elderly concessionary fares are typically half adult fare for cash while they are a flat HKD2 fare for holders of personalised smartcards; and that fares paid by cash do not qualify for transfer discounts (and in some cases do not qualify for short-distance discounts).
JERSEY - fares paid to the driver cost GBP/JEP3 in cash, but £2.55 by contactless or app and £2.25 by Avanchi smartcard.
KUWAIT - cash on board appears to be the only way to pay single fares. All buses appear to have the same fare of KWD 0.250. A daily ticket exists for KWD 1.000, but is only valid on the operator from which you bought it. This is not particularly good value because all routes are operated by 3 different operators, and there is no way to tell when the next bus operated by your chosen operator will arrive.
MACAU - all buses accept cash on board. The cash fare is MOP6 for all buses (HKD6 also accepted). The fare is MOP3 when paid by Macau Pass smartcard. Physical Macau Passes can be purchased using cash for a non-refundable MOP30 + MOP100 initial topup (can be spent in convenience stores too). A Macau Pass app exists.
NORTH MACEDONIA - Skopje - it is not possible to buy tickets on board. Tickets must be bought from convenience kiosks spread around the city. Card is not always accepted. The kiosks are not open for the full duration of bus operating times, and are not always well-located.
NEW ZEALAND - Christchurch - paying cash to the driver costs NZD4 and officially permits one transfer within 2 hours, while using the Metrocard smartcard costs NZD3 and officially allows unlimited boardings within 2 hours of the first boarding; the Metrocard fare also has a daily cap of NZD6. The Metrocard costs a non-refundable NZD5, is sold in limited places, and requires personal information to be provided. The owner of a convenience store only accepted cash to purchase a Metrocard from him. He entered my personal information into a dedicated Metrocard machine.
Wellington - using the Snapper smartcard gives at least 25% discount on single fares versus paying cash to the driver. It is possible to purchase and top up the card using cash at retailers, but not at machines. Retailers may choose how much to charge for the card itself - typically NZD10. Top ups incur an additional 25c fee, and may incur a Visa/Mastercard surcharge from the retailer (using a local bank card with the EFTPOS system typically doesn't incur a surcharge). Contactless and cash are accepted on the airport bus for the same fare of $11.50, which is more expensive than the Snapper price of $8.95. However, buying daily passes on board is the same price whether you use cash, contactless (available on the airport bus only) or Snapper.
OMAN - cash on board appears to be the only way to pay single fares in Muscat. It may be possible to pay cash on board for long distance buses, but the operator's preference appears to be to pay at the bus station in advance.
QATAR - Doha - it is preferred for bus fares to be paid with a Karwa smart card. Typical fares are QAR 3 or 4, but in theory drivers also accept QAR10 cash as a single fare. When I visited several times in 2018, drivers were meant to sell a two-journey single-use smartcard for QAR10 on board. This was sold at the airport which took cards, but once when the desk was closed, I had to proceed to the bus. The driver denied the existence of this smartcard and indicated that we could travel for free, but when I got to my destination he refused to open the doors unless I gave him QAR5 cash. I was also able to buy this smartcard at a bus station where only cash was accepted.
SERBIA - Belgrade - buses are currently free, but when I visited in 2023 they were not free. It was not possible to buy tickets on board. Buying physical tickets was only possible at 5 offices spread around the city, and not at the airport. Cash was the only payment method accepted at those offices. The only other way to pay was using an app or sending an SMS from a Serbian phone number. The public transport system additionally includes some express minibuses which are not free. Payment for these is by cash to the driver.
SLOVENIA - Ljubljana - cash is not accepted on board, but contactless is. It appears to be possible to pay cash at machines spread around the city, by purchasing a smartcard for EUR2. According to the website, this is refundable in some circumstances.
Koper/Izola/Piran - it appears that cash is not accepted on board, but contactless is.
Long distance buses accept cash. For buses in other cities, the acceptance of cash on board appears to vary.
SWITZERLAND - Geneva and Basel - tickets are not sold on board but from machines at large bus stops. Tram stops also have machines. Not all machines accept cash (sometimes they take EUR coins too). Hotel stays include free transportation, so most tourists do not need to buy tickets.
Montreux - when I visited in 2019, tickets were sold by a machine on board rather than the driver. Some buses' machines accepted cash and others didn't.
In most of Switzerland, single bus fares are priced at a level where the majority of bus users would save with an annual/monthly/weekly/daily pass, so buying tickets from the driver is extremely rare. But at least in German-speaking areas I think it is possible to pay cash to the driver if you really want to.
Norway: in 2023 cash was the only way to pay onboard (at least in Oslo and Stavanger) - in a cashless society to boot!
Stavanger - when I visited in 2017, the local bus company website said the fare from the airport to Sandnes was NOK 33, however when I boarded with cash in hand, the driver made me pay an on-board surcharge of NOK 20. I gave him twenty 1kr coins. There was nowhere to buy a physical ticket at the airport, but apparently there was an app. At the bus station in Sandnes, there was a card-only ticket machine which charged me NOK 33.
