Tailgates are expensive to replace, and now you have the camera lens and wiring in it. Sooooo yes it can be a "thing". Just depends how much someone wants their truck to "look" after they have done something stupid to it. Tailgates in the 90's, could run as much as $800 to $1200 bucks with the little chrome/polished beauty piece(appliqué) attached. MAC
A monkey can remove a tailgate and probably do it very quickly. Any sort of locking mechanism would be a great deterrent. Unfortunately, in these days, of crack-heads taking anything "easy," it's worth the investment of a lock. I had a fully-shaved (with interior handle) tailgate on my S10 and installed a lock.