Anyone travelling under such a mistaken assumption would have to fail to read, and fail to comply with:
- their booking site's terms - which will include a term requiring you to collect your ticket before travel, for example Trainline's condition 4.2says:
- Once you’ve booked, we’ll get your tickets to you as soon as possible, and always before your train, coach or bus departs.
- ...
- Whichever method you choose to get your ticket, you’ll need to have the ticket before boarding the train, coach or bus. For some services, it may be that collection at the station is the only possible option so you will need to leave enough time to collect your ticket before boarding your train. If you don’t show a valid ticket when asked, you’ll be responsible for paying your full fare again as well as a penalty fare
- the National Rail Conditions of Travel - which will be linked to during the booking process, and whiich state (para. 6.1):
- You must have a valid Ticket to travel before you board a train where there was the opportunity to buy one
- the 'readily visible' Penalty Fare signage displayed before they reached the platform.
And, in the case of a Merseyrail operated station as here, they would also have to walk past a booking office that's open.
Whilst ignorance of the law isn't a defence, I can appreciate that not everyone will read the first two documents - after all, who ever really reads the small print.
But failure to heed the latter two clues that - who knew - you actually need a ticket on you before boarding? Sorry, that's on them.