I'm not sure what equivalent you could have for computer service to provide the same baseline of consumer trust; peek on craigslist and you'll find dozens of computer service postings for even a small town, and in large cities it gets even bigger. I agree that it's probably an area that could benefit from a loosely centralized provider, but adoption seems like it will be very difficult.
Have you heard of IT certifications?, each vendor provides certifications based of their technologies, Microsoft has a lot of different certification programs.
If the client only wants to know the basic usage of a program, the service could pair it with another person not certified. If it's a company requiring for help or a developer in their home, he could request for "advanced service" and then a certified person could help in the specific field of the problem.
You can have a reputation system, with badges that determine how the person has being helpful, reviews from the clients etc.
You need a TLC license, at least in NY. Insurance, exams and getting a car. Uber in NY requires TLC. Some other states in US are more relaxed.
BestBuy could extend their GeekSquad service by incorporating other vendors into the service line. Half of computer problems require physical touch of the computer. I guess what you wanted to do is to turn SuperUser on stackexchange into a paid subscription, allowing people to pay a few $$ to do remote help, and a platform for people to sell their computer help service.
