Yes, Capitol Hill Is Slippery -- Back To You, Kent!

Why not just plow everywhere you drive?

Because you have to drive a lot slower when you're plowing, and your job is to plow streets in order of priority, which means getting to the bus routes and main arterials asap so that you can plow them. If you plow on your way there, you won't get to the priority streets until much later. So while everybody along your route might be happy, there will be many, many more unhappy people stuck on buses somewhere.