Kinda like a toll booth would make you susceptible to the same thing on the bridge. The problem with both of those schemes is that there are a number of except

Kinda like a toll booth would make you susceptible to the same thing on the bridge. The problem with both of those schemes is that there are a number of exceptions: people who live in the region, people who spend the night in the city... You don't want to place the burden of checking your hotel reservation on a train employee during a 5 minute ride or at a toll booth.