that is weird how a bus could work like that. Heck you can get get anywhere you want in the city paying the bus fare once. Then once more to get back no matter how far it is or how many times you may need to transfer busses. You simply get another transfer. It is a way to make it easy for even the lowest paid workers to get where they need to go when they need to go. Even city trams you buy a day pass that gives parking and unlimited travel for 12 hours or so. It makes money flow much better as well as labor and people
Guess the put a penny in your shoe which is the same as a 10 yen coin works in many countries, but it is also for good luck