Or, enforce existing laws against theft ... "Ban insecure vehicles" is chasing the technology of locks; there's always another circumvention.
This is true in absolute terms but over simplified because it glosses over the differences in scale. We require cars to have seatbelts because even though people still die in crashes, it’s a statistically certainty that many fewer die when seatbelts are used. Setting minimum standards is a critical function of governments in maintaining healthy markets because it prevents cheating from being cost effective. If you ma…
Seatbelts are not adversarial. A better seatbelt does not encourage other drivers to crash their cars into you even harder or anything like that, it's people versus nature.
Security systems are in a permanent arms race, people versus people. You could have a more expensive lock that requires a more expensive device to defeat, but this makes your car more expensive to make, so it has a higher price, so it becomes a more valuable target, and so on.