Pardon me for swimming against the tide, but IMO licenses are just another way for government to tax its citizens.
If I want to hire Joe Schmo to build me a fence or add a room, it's my business to make sure I don't get ripped off. NOT the government's.
Then you can't complain when the fence prematurely falls down and the guy is long gone.
Most county ordinances for fences are so involved you really do need a licensed contractor just to understand the regulations so your home owner's insurance will cover your liability.
I don't condone the over regulation of construction, but when something dire happens even many posters here will clammer for more oversight and try to make it someone elses responsiblity.