They've been 3D-printed: https://github.com/Xyl2k/TSA-Travel-Sentry-master-keys
Earlier this year I heard an announcement in the airport for someone to return to the ticket counter to unlock their luggage. If they can't access your luggage, will they cut their way in or will they simply pull your bag and you until you unlock it? Is theft from bags a major problem? I remember seeing a piece on it on one of those prime time news shows in the '90s which makes cynical me now think it was completely overblown. Maybe I worry less because I'm not packing electronics, just tents and snowshoes and the like.or attach a real lock and force the TSA to use their bolt cutters
It's not just TSA going through your luggage. Baggage handlers have been caught going through bags, if they find anything good they pull the tag and put it on a plane going somewhere else. Your bag gets lost, evidence of the theft is lost and they profit.