Despite being completely “drive by wire”, (modern) cars are not just “computers on wheels”. For starters: cars have moving parts; Your phone doesn’t (or does but barely). They’re complex beasts.
Probably most folks would think Apple could build a car -- and something being a computer on wheels Apple could handle, its more like Apple probably doesn't like the economics of it.. iphones and software services are pretty lucrative, and worst case scenario you ask the person to bring in their phone to get a replacement.. when you scale that up to building service centers, paying mechanics, building huge factories that produce a small number of cars per day compared to the 1 million iphones per day it would be a losing part of the business in both profit margin and risk for years even if they end up being pretty successful with it eventually..
I dont know why you got downvoted. Servicing cars is very different from handling what Apple is currently selling and definitely not remotely the same. So it’s definitely a good question how or why Apple would enter the car market.