If he can't he shouldn't be a general contractor

Anyone who does work for a general contractor and is not a direct employee of that contractor is a sub-contractor. Regardless of who sets the price. The subcontractors work within the contract set between the general contractor and homeowner. Hence sub-contractor.

General Contractor Lic.

So they can work as a general contractor and not have to work for someone else.

An insured contractor is a contractor who carries a Commercial General Liability Insurance Policy.