It was incredibly rampant in my area for years. When everyone started putting light bars on their cars the theft went out of control. It's only recently slowed down but still enough of a problem that parking with expensive lights is a genuine concern around here and I'm sure this isn't the only place. For a while you pretty much had to mount your light bar behind in the grill where it couldn't be accessed.Remember when everyone thought their fender flares would get stolen?
People have been mounting lights to the outside of their rigs for decades. I don’t think rampant theft of off-road lights is a problem in most areas.