It would be much less dangerous and more ethical to just steal all the hitches. It looks like only a couple of them are locked, but they're combination bike locks which should be easy to bypass if the core is exposed through the cylinder.
Somebody could be injured or die between vehicles if trucks pull each other in a crowded lot or wires/rope/straps suddenly become tensioned. Somebody could also be injured by walking into these, or it could damage another vehicle. Ethics and morality are a spectrum, one bad can be more good than another.