I have to agree with beth.
If you think driving a city bus isnt skilled labor, then you really dont have a clue as to what you are talking about.
A bus is on average about 40 feet long, with some of them being articulated (they bend in the middle) and that makes them as much as 70 feet long.
A driver must be able to manuever them in city traffic safely.
That means he must watch every corner when he makes turns, he must watch traffic, he must be able to judge distances for stopping, turning, pulling away from bus stops, etc.
Of course while he is doing this he is also responsible for the safety of his passengers, so he must watch them to.
He must be able to recognize all of the blind spots in his mirrors, and know when there is a person or an object in those blind spots.
He must also have a working knowledge of the bus operating systems.
He must be familiar with how the air brakes work, how his fuel system works, and all of the other systems.
He does a "walkaround" inspection before he leaves the garage at the start of his shift, and reports any problems he finds to maintenance to get them fixed.
Driving a city transit bus is skilled labor.
Oh, and lets not forget that he also must know how tall his bus is so that he knows if he can clear any tunnels or overhangs on his route.