Theft deterrent for older cars is the simple fact that nobody stealing cars knows how to drive manuals anymore.🙃
I partially proved this when I took my 2000 Civic to Costco for new tires and they had to find someone who knew how to drive manuals. None of the young techs they had knew how to!
The Flipper Zero is 5 years old this month, but despite failing to cause nuclear armageddon, Ebay still refuses to let you sell one. A policy that totally contradicts itself when they are more than happy to sell you these equally nefarious hacking tools.