For most people, you'll have to take it to the mechanic and it'll cost you an arm and a leg... wait that sounds familiar...
In addition, when a vehicle reaches the point where any common repair costs more than it's current market value, it's basically considered worthless and only desperate people buy them. How long does it take an apple product to reach that point? A year?
For traditional cars, as long as it's not a completely blown motor or transmission or a extensive front end collision, it's always economically viable to repair them.