> Failing to implement even the most basic security measure, which is considered industry standard, in a high-value product that is known to be very attractive to thieves and then selling that product to consumers with no warning that "unlike most other cars on the market, which have many layers of security features, this car can be stolen using a cheap toy" makes the inevitable thefts absolutely Kia's fault.
I don't think this logic works. If you buy a classic vehicle, they don't have these kinds of things either. People make replicas that likewise don't. And there is no clear line here. Basically any car can be stolen by, if nothing else, replacing the car's computer with one that accepts the thief's key.
Meanwhile a car is a large purchase where people can reasonably be expected to do some research. If you're about to buy a car you should read some reviews, and the reviewers should tell you if their security is bad. Then you know and can make your decision. People who learn of this may want to buy a different car, or take some other countermeasures if they buy this one.
Kia doesn't have any kind of a monopoly in this market. There are many other carmakers. Maybe you don't care that their security is bad because you always park your car in a garage. Maybe you like the discount you got because other buyers wanted a car with better security. Why does it have to be illegal, instead of letting the market sort it out in the presence of actual competition?