individuals who were basically competing to see who could tag the most dangerous/obscure/hard to reach areas

There is at least some point to that. Not much, but something.

I do like the "naive" style portrayed in your opening shot. Whoever did that gets more points for being socially responsible and not painting over the warning label.

Yeah, I think it was community endorsed. Perhaps a local school. It is far, far too open to be illegally done :D