You may be right -- today. Elon and Tesla can make their own decision for now, IMHO while they primarily cater to a majority of cash-rich enthusiasts where Infotainment may not be a more major determining factor in purchase of their vehicle. IMHO as Tesla enters mass markets and want to compete with a growing number of EV players who are much more mature competing against others, Elon won't be able to stay only on his vision, but will have to compromise more to balance what the masses really want and demand, with pushing his vision forward -- especially for Tesla if they continue to only make money off car sales, not also service.
Some notable auto brands were long-time hold-outs especially in the early years when CarPlay and Android Auto were lets just say "more than problematic, and far from maturity", saying they would only implement their own Infotainment interfaces for all sort of reasons, but as more and more mfgrs are implementing these sort of common consumer-oriented interfaces across their model line, I suggest Tesla may have to change their approach. The variable is, Tesla COULD implement something as good or better, but they have made almost no movement in that direction after several years, and the longer they wait, the further behind they get, and it will take even more resource to catch-up, let alone move ahead and maintain a unique 1-off interface.
Other brands, like say Toyota/Lexus that initially went the route of doing their own thing, suffered(s) from lack of functionality, appearing to be behind the times compared to others except every 6-7 years when there is a major model refresh and they (temporarily) catch up. Additionally, their own unique app interfaces couldn't gain traction with sufficient 3rd party players, so IMHO as a previous Lexus owner, there wasn't much in terms of useful and reliable apps that became available. Using their own interface and smartphone connectivity still didn't help the consumer who would likely prefer having a common interface for basic Infotainment function and capabilities across mfgrs for families with multiple auto brands in their garage. I'm a pretty technical guy, but it was hard keeping track of the nuances to use and access similar Infotainment functions in my Lexus and MBZ as I switched between them. I bet it's even harder for some others.
Check out
this site, scroll down and see what major auto mfgrs in both the luxury and mass market area Tesla wants to participate in, that's not committed to the CarPlay (and likely Android Auto) interfaces.