I'd guess Tesla has a 5$ headlight and a 1995$ encrypted ROM to brick your car if you go outside their supply chain

At some level hardware is hardware. If the headlight has a module that needs to to authenticate then someone would offer a "send in your core and we replace all the shattered plastic and glue it back together" service. Such services are commonplace in the aftermarket parts industry. Usually they just charge you for the core and credit you when the core you send in is good but for rare/low volume stuff you have to send in a core before they do anything which is the business model I would expect to see for something like a Tesla headlight.

Have a look at Rich Rebuilds on youtube. There is a long list of things Tesla can do if you go outside of their blessed supply chain. Including, for example, revoking super charger rights. They might not do it over a broken headlight, but it's a bet you have to take.

> Such services are commonplace in the aftermarket parts industry.

Such services are available for the most common vehicles, not every vehicle. It also takes time to prepare, and if the market is small (Tesla is still a niche luxury car), then why even bother?

I know, I know, there are cities where it's a relatively common vehicle. That's not enough, it has to be relatively common on at least one whole continent.

But then the buyer is having to pay out of pocket for a warranty repair.