richy it isn't that daft a question mate to be honest, there is a firm round here, and I don't know how they do it legally, but lots of vans and everyone is self employed but all with the same company name on the van, it is nearly all commercial but I can't answer your question, as I don't know who owns the vans and how they work it, but as far as I know it isn't a franchise, so it is a question worth asking.
I can only imagine they are breaking employment laws or have found an in between route, or they all sole traders, trading in the same company name and brand, but with separate accounts etc, but I can't see that being easy to run or legal