I've had a read through this thread and I'd like to report my observations.
1. Drivers rarely bother to set the fare stage, and just leave it set to the terminus. A short hop from say Barnsley to Birdwell on the X17 on a Sunday, you get a ticket for £2 valid to Wirksworth some 54km away as the crow flies! (unless you're like me and have actually done the full journey for a laugh

)
2. Nottingham City Transport operate a 'exact cash fare only' and are unable to give change. (from what I've seen, the passenger inserts the cash into a slot which the driver can see, and press a button to drop the cash into a box below if the correct fare has been inserted. NCT's boarding is the fastest I've seen in the region, with ITSO card scanners, barcode scanners and the aforementioned cash system.
3. The Peak Sightseer service operated by Stagecoach Yorkshire in Chesterfield does not offer the £2 fare, instead charging £9.50 for a day ticket(Same as the local Gold Dayrider) and £5.50 for people with a valid ENCTS card or a Manchester/Derbyshire wayfarer. Is this the same for other sightseer services? They also offer a £4 single ticket for 'short hops' on the Chesterfield/South Sheffield feeder services.
4. I live relatively close to my town centre, as such the price of a single ticket to town is £1.80 (yes sometimes I am lazy

). I usually have to remind the driver that I am to save 20p!
5. I notice that on Stagecoach services in Sheffield, passengers getting on sometimes present their phone to the ticket machine and expect it to be 'tap on' like First and (I think) TM Travel. They usually shoot the driver a blank expression wondering why the machine hadn't reacted; which I admit is rather funny.
(Once I witnessed a passenger get off a First 24 service and run up to the bus I was on (Stagecoach X17) and ask if she could use this bus to 'tap off' since she had forgotten on the First bus! Oh the joys)
Morally I believe that a cash option should be available, whether that be NCT's approach with exact fares, or a London 'Oyster Card' approach. A nation-wide ITSO scheme sounds like a good option, but comes with all manner of issues previously noted in the thread.