Some issues and suggestions:
1. Add more types of buses (some the actually turns without destroying half of the city.
2. When you spawn a bus check if a bus is already at the spawn point before spawning.
3. Bus stops - do not automatic stop the bus, instead the player once on the white marker needs to open the doors and a timer will count down for who long he needs to stay.
4. Paying - don't know if there is a regular rate for buses when going up as a passenger.
5. GPS route - the current routing system based on GTA V GPS is bad - It needs to give the player the correct path of driving.
6. Bus route - there are good bus routes on the internet that uses in game stops. I think it is better to see where the stops are and create routes based on that.
7. Airport rental bus job - add a job to take passengers from the airport terminals to the car rental area (allow renting only from the actual car rental parking's in the airport area)