There's no way to design vehicles that can't be made unsafe by a mechanic making a mistake. Even for purely mechanical things like brakes, a mechanic can leave

There's no way to design vehicles that can't be made unsafe by a mechanic making a mistake. Even for purely mechanical things like brakes, a mechanic can leave out a bolt or crack a structural member so that it breaks on the road. EVs require careful procedures, for instance to make sure that any of the high-voltage wires can't rub against anything and wear through the insulation. Dealer mechanics make mistakes too, but at least they're trained on the specific car, and they can collect data to notice a pattern of things breaking after certain people worked on them.