A lot of early adopters were probably worried that Tesla would go out of business and they wouldn't be able to get parts. Tesla is still in business and there still aren't parts. Hopefully enough of the current Tesla models will end up on the road to make it profitable for aftermarket suppliers to make some parts. So far it doesn't seem like that is happening at very much scale.
Parts are hard to come by for their mass market models too, it's crazy.
I've done 3 projects on my 2004 BMW post 2012 (where as time passed, more parts become available); one of the last years before everything became more computer integrated, where there weren't significant, cheap, readily available parts
- Xenon Headlight Baskets; factory headlights only sold as a sealed unit (that would likely suffer the same burn issue), aftermarket whole units don't have self leveling to be road legal; Had to find from a crashed 2006 on eBay and modify.
- Windshield washer pump. This simple pump didn't become readily available in parts stores until about 2013. The factory unit costs 10x what it should cost.
- Valve cover gasket; the best one is the OEM bmw, brand, any aftermarket part is likely to leak sooner rather than later.