I have seen petroglyphs that have been destroyed or damaged far from any known route that an illegal would take. There are simply people who do this kind of thing, even Americans. They are as bad as the Taliban.
I have seen this petroglyph, located in Utah, in person. You can notice a mark on the left side line of the large figure, around where his stomach is, between the spiral and the smaller figure on his right. This is a bullet hole, where someone used the 1000 year old petroglyph for target practice.
Weren’t the petroglyphs themselves a sort of graffiti, done centuries ago?