Heres one for you Spectatorz....
In the state of Michigan, we have a general contactors license for maintenance and alterations, a residential builders license, and licences for each specialty (roofing, siding, painting, etc). Each only requires the passing of a written exam and a fee. That enables you to work any where in the state.
For hvac, elect, plumb; its the same as it is in most states. You have to work throught the apprentice program.
But heres the kicker. All the licenses are requirements for residential work over 600.00 in value. Yet there is no commercial requirements. I had my lawyer actaully check into it for me. Basically what the law says is: If I, a painter, bid a residential paint job for 2000.00, the state would required me to have the Michigan Painting Contractors License (sure). Yet, if I wanted to bid the building of a Home Depot store for the Home Depot company, the state requires no license of me.
Another loophole in the law is for the maintenance and alterations license. If I was to do a remodel for a customer, I could tear down the entire house, and rebuild it, as long as I leave 1 wall standing the entire time, I'm not required to have any license at all.