At Sunset Nursery School, a cooperative school where parents help running the place, sand box sifting was the one job no one wanted. It really was a long slog and you felt in the end really cleaning the box was hopeless.
I suspect this less about lazy city employees and more about liability issues. Cat poop is one thing, but human feces, needles, broken glass, etc. is challenging.
As a guy who still pays city taxes, it's fine with me if they spend the money on bigger issues.