I get it, it sounds ridiculous that you'd want to change the code on your car's computer. However it's like GM declaring that, for the sake of public safety, only their dealerships should be able to perform brake jobs. What do you think that would do to the price of a brake job, if the number of options were controlled and you weren't even allowed to do it yourself?
Cars are become more and more tied to their central computers. Look at a Tesla, the windows are even controlled by the computer. If something breaks you can't even legal diagnose it, if it involves looking a the bus data the computer spits out.
I read an article about the value of old John Deere farm equipment going up, because there's literally nothing a farmer can fix on a new tractor. They've locked them into service contracts without competition and their productivity is at the mercy of the availability of service techs if anything goes wrong.