This is already happening in my neighborhood/county at least. We separate our stuff but we've seen other cans get ticketed for contaminated receptacles. (I think it's mostly just warnings now, unless you are a habitual offender.)

Still, this is all a bunch of crap. This is a perfect thing to centralize and no amount of shaming/fining the population is going to actually solve the problem in the long run without causing major headaches and graft for the waste management companies (oh, the stories I could tell about them).