They generally are, yes. On most other cars, you can get the software and interfaces to interact with them as the dealer can, if you're willing to jump through

They generally are, yes. On most other cars, you can get the software and interfaces to interact with them as the dealer can, if you're willing to jump through a few hoops. Various service procedures require this sort of interaction (often a coolant replacement requires some bleeding procedures to get the air out, brake fluid flushing requires some toggling of the ABS controller valves, etc). Or, sometimes, there's just an easy diagnostic procedure you can do. "This problem could be caused by valve A being bad - can you test valve A? It's not moving as commanded? Ok, I'll go replace it." I can do none of that on a Tesla. I can't even access the diagnostic screens built into the car without a rolling code generator - even if I own the car free and clear. And that's a problem.