No, one can do that anyway. There is basically no real way to stop folks from modifying their cars. It can be made more difficult, sure.

This is about selling tools and access. It's another profit pipeline for car OEMs.

I don’t think that’s the reason, seeing as a car is already endangering everyone around it by existing. More likely about keeping the tooling to diagnose issues proprietary and expensive.

That kind of thing is always the stated justification but never the real reason.

Almost invariably when that excuse is trotted out, there are are usually many things that are much more common that are also far more dangerous. For example, texting while driving or driving with bald tires in the wet are both 100x more dangerous than anything almost anybody would do by modifying the car's software.

Four 9/11s worth of people die every year from drunk driving. If we can't even get that under control, I don't see why being able to modify your own car is a big deal.