I think it's still an issue that starts when the first radio gets damaged. That creates a secondary market for replacement radios, so theft occurs. Then, the person owning the car where the radio was stolen is now looking in that same secondary market for a replacement...and the chain never stops.

Similar for things like 3rd row removable seats and tailgates on trucks. Craigslist and eBay have more of these for sale than would make sense if they weren't being stolen.