Is it possible to ride a bus as a passenger? Also, how do I get out?
This is a bug. Per the game manual, Wei can only hire taxis, and as such it shouldn't be possible to become a passenger on a minibus.
While I've never had this happen myself to test, based on multiple accounts[1] [2] of this happening to other people it seems that there's no way for you to exit a minibus if you're unfortunate enough to get stuck on one, except by causing the game to reload you at a different point.