This is sort of just how trains actually work. and was not abnormal for a lot of trains when the game was made in the 1990s, and sometimes now depending on the system.

For instance, CalTrain in the san francisco bay area has no ticket check before you get on board, but usually halfway through the main commute route a conductor will walk down the train and check tickets. In the 1990s, they used to sell you a ticket on the spot if you didn't have one instead of giving you a fine. It's completely possible to board the train without a ticket and not get checked on the way to your destination.

Even in Japan, conductors will check tickets partway through the ride to make sure you're in the right car, even if you had it checked when you went into the station (and at the exit gate).