My overall thought is that the abolition of human on-board sales would be at best unnecessary change, and at worst detrimental.
The DOO debate
is not something I want to get into particularly, but though door operation can be debated, having someone on the train to assist passengers can never be a bad thing.
If you want to override the default, buy a ticket elsewhere.
The problem with this policy is that it discourages use of the train. Part the appeal is the ability to just walk down to the station and hop on a train, buying whatever ticket is needed actually at the station rather than beforehand. Ticket offices are not, and will never be, open 24/7, and ticket machines are unreliable and difficult for some to use.
Actually there is a big drive towards e-tickets at the moment; several retailers have already switched the default to e-tickets and many more are following.
Yes, but not everyone can use them. It is not a requirement to travel by train to own a smartphone to display your ticket, a printer to print it, a credit/debit card to pay for it etc.
I am of the opinion that, as long as cash survives in mainstream use, cash payment for public transport will need to survive. I am firmly against TfL's policy of charging double cash fares.
Either you take a payment card with sufficient funds on it for the journey or you load a ticket onto a smart card. Maybe there would be cash smart cards but it is not a necessary requirement.
It
is a necessary requirement, because children cannot be issued credit cards. Some kids' bank accounts are now starting to offer debit cards, but many parents don't want their children to have this much responsibility, or risk if it is lost.
As for loading tickets onto smartcards, I still cannot figure out how to put anything shorter than a weekly season ticket onto my ITSO card. Unless this flaw is fixed. I will not be switching over.