Sure, but sometimes your ability to customise a product to do whatever you want with it can also affect others, and at that point your rights and theirs have to be balanced.

My go-to example of this is modern communication devices like phones and tablets. There are obvious concerns about security and privacy with such devices, and obvious arguments in favour of the hardware design and software running on them being open to audit and verification so owners know their device isn't quietly betraying them. Those naturally lead to suggestions that all firmware should be open to owner modification, black boxes should not exist, etc.

What a lot of people don't realise is that if you let some idiot who doesn't know what he's doing mess around with the firmware driving the actual radio components in those devices, it's entirely possible for just a single device to cause widespread disruption that could interfere with the operation of numerous other devices in the area, with obvious implications for safety, security, and general quality of life for everyone else affected.

Even fewer people realise that the technology for isolating a rogue unit (which exist anyway from time to time due to things like hardware failure, manufacturing defects or software bugs) is very limited in its capabilities, because unfortunately the laws of physics still take precedence over whatever laws or regulations we choose to create as a society. In other words, not only can one rogue device cause chaos, it can cause chaos for an extended period because even the professionals operating the network have limited powers to do anything about it quickly.

To finish by returning to your own analogy, sure, I would have concerns about a car refusing to move until it's towed to a service centre authorised by the manufacturer if its tyres didn't have enough tread. That's obviously a form of lock-in that isn't in the owner's interests. However, I would have fewer concerns about a car refusing to move if its tyres didn't have enough tread to be safe until the problem was fixed, as long as any suitable method that made the car safe would immediately remove that block.

There's a huge practical difference between gearheads modifying the physical parts of their cars and a world where any Tesla buyer could as easily tweak engine, breaking etc. performance as they could download an app or re-flash their phone. You'd have idiots who'd otherwise never bothered to modify their cars dying as a result of trying to rice up their ride.

It's the same situation as RC planes and drones. The RC community had a natural selection bias for decades and wasn't worth regulating, then drones became available on the mass-market resulting in a bunch of idiocy that regulators needed to scramble to keep up with.

I think car manufacturers are rightly paranoid about that. There's a lot of profoundly stupid and unsafe stuff you could trivially do with a Tesla if you had access to the software, and if it was easy to install those sorts of things people would do so en masse.

Its also more technically feasible to prevent modification, and speaking as a fellow road user, I think I'd rather you run with stock firmware.

Until the courts can provide adequate compensation to the family of someone was was killed or to a crash victim who received life-changing injuries, I don't think that's going to be a compelling argument in this sort of situation.