I propose, somewhat tautologically, that the primary reason why car theft is generally well policed (in USA, where my lived experiences have primarily been) is that it's generally a small enough problem for most police departments to get their arms around because of basic anti theft technology.

I believe the Kia/Hyundai debacle of the last few years supports this idea:

> So far this year, Minneapolis police have received 1,899 Kia and Hyundai theft reports, nearly 18 times the number for the same period in 2022. [1]

[1]: https://apnews.com/article/hyundai-kia-tiktok-theft-stolen-8...