I can buy a 104 key mechanical keyboard for under $75 retail. That's 104 switches, 104 labelled button caps, a circuit board, controller and USB interface, with reliability likely much better than any other moving part found on an automobile.

That is very factually wrong. The reliability will be worse. That $75 keyboard is going to be used be hundreds of thousands of people, not millions. There is no safety involved. No one is testing to see how sunscreen and 50 other liquids interact with it. Dump a sugary drink on your car buttons, they will still work. Do that on your keyboard and it wont.