Bus people are a whole sub culture. Just because you ride a bus doesn't make you bus people, and just cause you have a car doesn't mean you are not bus people. The people that run up on you asking for change at gas stations or anywhere are bus people. Overall you are a bus person if you are super ghetto and don't know how to function with the rest of society.
The plural and singular of this word is the same : Bus People
I just saw a piece of poop fall out of that "Bus people's" pant leg as he asked me for some change.