We have to wash ours as well. glass, aluminum plates, Styrofoam etc. The cardboard has to be a certain size or they'll leave it at the curb.
It all goes to a recycling centre to be sorted and sold and I love it.
The thing that really burns my *** is people of all ages that just toss their garbage out the window of their car or throw it while walking. Just plain lazy and costs the tax payers money because someone has to pick it up.
Some groups will gather in a certain neighbourhood and walk picking up garbage