Railroad wiring is a common target too of course.
Guardrails seem to be immune here though.
https://www.king5.com/article/news/local/copper-wire-theft-l...
You don't need things to be bad to have theft, especially of small or easy to steal things. It is one of those crimes that sticks around regardless of how "good" or "bad" things are, though admittedly it seems to be a bit less when times are good. I moved from the midwest, US to Norway - and theft seems to be one of the more common crimes. Things really aren't especially bad here from my point of view.
Regardless, You still have thrill seekers, folks that mismanage money, folks that slip through the state support cracks, drug users and alcoholics, gamblers, teens whose parents don't provide for them (both real and perceived) and so on.