Sounds a good idea, however it isn't such an easy thing to set up and administer.
You would have to have a central body who organised the admin side. The reason national companies use other national companies to carry out their work is because everything is centralised and they are assured of recieving a uniform service (on paper at least). They are able to provide them with the KPI's they require, these all need to be collated, etc etc, etc.
You then have to demonstrate that the people doing the work are trained to the same standard., are adequatley insured, the central body would also need insurance.
Ask Chem-Dry if you can visit their headquarters, you'll be gobsmacked.