Didn't they fix that?

Yes. Even the older cars have a software patch to tie engine start to the keyless entry.

And yet the 14 year-olds in my city keep stealing them every day. I'm pretty sure you're mistaken about the fix for older cars.

You are correct. Some models couldn't get the software update, so now they are getting a more secure ignition cylinder.

https://www.cars.com/articles/kia-introduces-free-anti-theft...