The point about the car isn't really valid. The margin on a car is far more than on a computer. Profit in IT is almost nothing most of the time.
If every computer supplier could have a shop in most towns then you would be able to pop along and get your PC fixed in the same way you do your car. But would you want to pay £40ph for the privalidge?
Working in a company with 300+ employees whose website has 2 million hits a month has shown that most hardware is reliable. Its very rare to had to call support for end user PC's and equally rare for the hardware.
To provide the level of service some people seem to want would cost far more than anyone would be willing to pay.
Thats not to say small improvements couldn't be made for miminal cost.