Analogies are slippery in general, and the car analogy in particular is problematic.

I know a *lot* about engines; and have rebuilt a couple. That knowledge did me no good when my alternator went out in the corolla last year, halfway to Tucson. The battery quickly drained, the computer could not run, the car died. It is not practical to carry spare parts, given that Toyotas are pretty reliable.

With computers, the failures are almost always software; bugs that could be fixed but were not. This applies to any OS or application.

I fly light aircraft. The engines are orders of manitude more reliable than those in cars, partly because of strict maintenance and design requirements. Software in the control systems of expensive aircraft also are subject to rigid standards - standards that, if applied to NITs or home computers, would make them both hideously expensive and wonderfully reliable!

Steve