However, it doesn't miss the point.
Someone might assume that if they hold an Advance ticket from Newcastle to London but are offered a lift to Durham they could join their booked train there without problems. Of course, such an assumption would be incorrect and 'common sense' doesn't come into it - the regulations are clear.
The regulations banning alcohol are also clear and if someone is found breaking them common sense is again irrelevant. Some, like
flamingo, would apply common sense, others may not ... and there is no way an intending passenger could know which sort of person they would meet. Saying 'I assumed it would be OK' to one of the latter would get you nowhere.