The difference being, there's a mandatory "new user training" before you're allowed to operate a car. Take something like a riding lawn mower that doesn't require new user training, and you'd better believe manufacturers worry about things like "does the user know that letting off the brake means the mower will accelerate to full speed instantly?" You end up with people who know how to operate a riding lawn mower and those who don't, and it explains why many new mowers come with car-like accelerator and brake pedals (with "cruise control" for the classic crowd), and also why mowers will disconnect the battery if the operator isn't sitting in the seat.
If a new computer required mandatory training and a license to operate, these issues wouldn't be nearly as common. Besides, how many people are absolutely flummoxed by a manual transmission?