Here's a bizarre one:
A couple of years ago when camped in a California DNR campground, I was informed that the TT I was towing "counts" as a second vehicle; and since there was a two vehicle limit at each site, this meant that my family members who came along in their own car had to pay for and park in a second site!
I will add that this was the very first year they'd imposed a fee schedule on those lands, and I complained very bitterly about this ridiculous stricture, pointing out that in California State PARKS, a travel trailer/tow vehicle combo is counted as one vehicle. Hopefully CA DNR's changed that rule by now...