How do they get to be a G.C.?? (General Contractor)

In the state of TX to be a (G.C.) General Contractor you do not need a license or to prove to anyone you have any clue what you are doing.
Only some trades (sub-contractors) are required to have licenses. i.e. plumbers, electricians, h.v.a.c. installers/techs, and most engineers.
Contractors sometimes (most) have to register with a city and provide proof of insurance (usually 1million dollars general liability) and some make you provide a bond.
All licensed trades will pull their permits under that contractors General Permit on projects. Ultimately making him/her responsible for those trades actions. (note: do not pull the permit yourself, you want a G.C. to be liable)
Contractors essentially are there to negotiate what each trade does. i.e. budget, scope, timelines. And then contracts (signs a legal document as to what is going to progress in the agreement) that trade for that task within that projects total scope. That’s it. Of course, knowing quality trades helps the contractor. Having a solid idea of what it takes to accomplish the task in which he has taken on, and also the ability to communicate clearly with both the project owners (or designers/architects/permit departments/nosey neighbors/etc) as well as all of the trades in order to get the idea’s from 1 (or several) persons dreams and into a seamless reality.

(or maintaining the illusion of seamlessness in a storm of utter chaos all while managing to compete the task at hand.)