Forced to by insurance companies, or forced to by bad press like this, can do the trick too.
I don't know about these states but I live in a state where insurance is mandatory. I don't know if there are flip sides of the laws mandating insurers to insure, but if not, if the entire industry in my state followed suit for these cars, it would effectively take the cars off the roads. I can promise you the manufacturers would take note of such an outcome.
"Starting Jan. 25, State Farm Insurance agents in Louisiana are no longer doing business with owners of 105 Kia and Hyundai models that have been blacklisted because they are vulnerable to theft, employees told WWL-TV."
Scanning over it again, it still seems the correct interpretation of the text as written. But it is an easy mistake for a journalist to make, if you know that it's theft-only from some other article then I'd be wrong about my state comment.
The idea that insurance can drive this would still stand though. An entire customer base being told they can't insure will get attention. It would need to be an industry-wide thing, though, or the customer base may just change companies.
I hate Korean cars but this really isn't on kia or Hyundai since the existing motor vehicle import laws in the usa do not require cars to have immobilizers installed. pretty much every other import and domestic car has been installing them by default for over 20 years.