And the specialist might have to take it to other specialists because the diagnostics and repair equipment is so outrageously proprietary and specific nowadays that only one shop per major city can afford it.
Which at least partly because have become much more complex things. Complex systems with many electronic and mechanical systems interacting need complex tools to debug.
Only partly. There's no technical reason why you need to have 70 differently wired connectors to access the engine computer's UART port… and why they cost over a hundred dollars each.
Or why the error codes are kept secret from the user, resulting in only the dealership, not your local independent, being able to fix some things.
And also the requirement of specialist tools to do non-specialist jobs like set the engine timing, and then charging a lot for purchase of the tool. It will be interesting to see how serviceable electric cars become once they are old enough to start being parted out and the used market expands to those who 'just need something to go from A to B'.