Nowt you can do but get worked up. Decide whether marks on the bodywork are important, or not - do they affect the running? If no, then rise above chips, dents, door dings and scuffs. I also do not clean my car. I believe nobody will be interested in stealing a dirty scuffed-up car.
Even if you did catch the kids doing it, are you confident their parents would be cooperative about it?
I discovered one source of scuffs was the paper delivery lad - buckles on his bag. He didn't mean it, or even know he'd done it.
You can generally tell the deliberate ones, they're deeper and slightly wave up and down. Accidental scuffs tend to be shallow and straight.