I'm sure it happens, sometimes. Most of the time, the lawsuits for digging up someone's fiber optic cable or natgas line are so staggering that there are vario

I'm sure it happens, sometimes. Most of the time, the lawsuits for digging up someone's fiber optic cable or natgas line are so staggering that there are various "free" one-call services that mark buried objects. The public utilities all pool resources to fund it, so it's free in the sense that your utility bills pay for it. I know a guy who had a gig doing that and in addition to locate devices that are kind of like a giant telco wire toner, they do indeed sometimes walk around with a literal metal detector. Doesn't work very well on terracotta sewer pipe but those generally collapse in a couple decades as I've found out the hard way. Anyway, yeah, a dude with a metal detector walking around with a map of buried pipes in one hand saying "that's odd there's not supposed to be a pipe here"...