This is exactly the point. If your car is a lemon and always in the shop, at least it's trivial to get a rental, even if you're out of pocket the cash. Any number of car rental companies will drive a car out to your house or the shop where it is.

If your tractor is broken down and you need to bale that hay that's been drying in the fields today before the rain comes tomorrow and ruins it, you're screwed unless you can find a nearby farmer to help.