It probably also helps that they allow people to load at both the front and back of the bus, and they check tickets while the bus is in motion. Buses in the US

It probably also helps that they allow people to load at both the front and back of the bus, and they check tickets while the bus is in motion. Buses in the US generally have people load one at a time through the front door and everyone's ticket has to be checked or (even worse) they have to feed dollar bills through the machine. This greatly increases per-person load times, and exacerbates the bunching effect.