@bfluzin
There's a blistering obvious solution which train companies don't want to admit:

- all ticket checkers should be able to sell a ticket then and there with no markup / "penalty"
- if technical issues prevent that from working, just don't charge the people who can't successfully buy a ticket
- never refuse entry for any reason other than capacity

The problem isn't "it's harder for some people to get a ticket", the problem is "you're not letting people ride the train without a ticket"