Honestly I figure that with people throwing up on the floor, spilling drinks all over the place, stomping out cigarette butts, probably ashing on the seats, standing in the seats,etc...that a little tape residue on the metal back of a seat isn't really that big a deal. Maybe I'm not sensitive enough to the venues needs. I'm definitely not so fucking stupid as to put duct tape on dry wall. (slight edit)
The difference with all those other negatives is that they're not expressly linked to a specific population (tapers), but rather the general population. Not many concerts I attend include people vomiting on the floor, spilling drinks everywhere (well...a bit of that), stomping out butts, etc., (you must tape in a bunch of shitholes!), so I try to tread lightly since the backdrop for my actions isn't as severe as the ones you mention. While in the grand scheme of things a little sticky residue isn't a huge deal to most, I prefer to leave no footprint at all, if possible. Spending a few extra bucks on quality gaffers tape is a small price for me to pay to reduce my risk of pissing off the venue. And you beat me to it with your follow-up comment:
Edit: Whatever you use, make sure you take it with you when you leave.
Anyway...apologies if I came across harsh...I just thought of a newbie finding the comment "I don't worry too much about..." and extending that sentiment farther than it should go, and wanted to plug my $0.02.