I think our school buses are just made to be cheaper than city buses and are more lightweight and less fitted up with electric controls. Like some US cars have all kinds of bells and whistles to move seats, lock/unlcok doors and windows, pop the trunk/boot, heat up the driver's seat (yes!).... school buses are more stripped down, utilitarian, because of the wear and tear they will get (kids are kids) and the cost to the schools.

~S~