Well, that answers my question. I guess the solution will have to be something like the ugly floor to ceiling turnstile. Another option would be to make people leave instead of giving them a citation and letting them board the train.

I don't know if this is policy, but on Caltrain I have seen conductors make people get off the train if they didn't have a ticket. The funny thing is they are then miles from their starting or end point. Their choice is hopping the next train and hoping no-one catches them or buying a ticket. Either way they are delayed in getting where they want to go.