You can still walk right up to the parts department counter and order OEM replacement parts for anything on the vehicle, just like the dealer can. The computer

You can still walk right up to the parts department counter and order OEM replacement parts for anything on the vehicle, just like the dealer can. The computerized bits are well isolated control modules and are generally treated as black boxes which either work or are replaced as a unit. But that doesn't encompass the entire vehicle, the vast majority of the vehicle is still very servicable, all the mechanical bits haven't really changed that much from the 60s. I've rebuilt engines on cars and motorcycles, modern and old, many computerized with EFI, you generally don't worry about the inner workings of the computers unless you're modifying things. In my experience the more modern stuff is actually simpler having fewer vacuum lines and archaic rube goldberg machines for control systems.