It's absolutely true that engine parts can be made in a machine shop by a suitably talented artisan, so there remains a third party parts market for those things where there isn't for e.g. 20nm digital logic fabrication, NMC battery cells, etc...
But that's because one of those things is century old technology and the other isn't. It's not a business model thing, at all.
Audi instrument clusters, for 2021 models [1] — Audi appear to be willing to sell these to me, even though I don't own a car.
[2] seems to be a third party retailer.
[1] https://parts.audiusa.com/productSearch.aspx?&ukey_make=5792...
GP didn’t say that Audi doesn’t sell it, but that you can’t “second source” it:
> You can't get a dash display replacement for a 2021 Audi or whatever from anyone but Audi, etc...
The difference here is the dealer will sell you the parts most of the time no questions asked, no proof of ownership needed, no need to have the dealer install the part, etc etc. My understanding is that not even Tesla will sell you the parts, you have to bring the car in, they have the look it over, tell you what parts you need, and then you pay them to install it.
this is VERY VERY different than your Audi example
The display went out in my wife's 2018 Toyota, I went online and bought the part through a dealer and installed it myself.
That's not very possible to do with Tesla, and I think that's the point here.
The Tesla screen is available from Tesla's parts departments. You don't even need to own a car to buy it.
You don't need manufacturer support to repair most cars. Several car makers have left the industry, and their cars are still drivable and repairable. You can generally buy and repair cars with flood or wrecked title and repair them if you've got the time and patience; manufacturers will probably think you're crazy, but you can get service parts.