That's a totally flawed understanding of modern ICE vehicles.
There was an era of vacuum-line misery separating the 70s and 90s, where you'd almost certainly never get it back together and functioning good as new again with the literal miles of vacuum lines and solenoids.
But modern stuff, especially with just 4 cylinders, is relatively simple and entirely DIY servicable. Wiring harnesses have replaced all the vacuum lines, and everything has a physically unique connector pair, and the harness routing is well described in the service manual. So all the guesswork is gone there, honestly the worst part on new stuff is not overlooking any of the grounding lugs.
I share your attitude WRT modern EVs, but I bet if we just treat the controller and battery as black boxes we don't attempt to disassemble and service, the rest is just more of the same simple machinery except with no hazardous gasoline and motor oil to drain and handle.