Some people will steal anything. We had a year old, ragged out, on it's last legs CHEAP Wal-Mart gas grill stolen off the back of our Class C while it was in a parking lot. It was stolen, because I had checked all the straps on the hitchhaul on the Class C and the grill was still strapped in. We had stopped in to look at a replacement grill. They didn't have any of the cheap ones, but they did have more expensive. We decided that must have been the reason ours was stolen. We simply headed to the town we were staying at and bought one from that local Wal-Mart once they got them back in stock. There was an RV in the parking lot a few spaces away when we walked into the store, but it was pulling out of the parking lot when we came out. I had to retighten the ratchet straps on my hitchhaul.
If something is "borrowed" without prior permission, it's been stolen. Doesn't matter how expensive or how cheap.