Reno, your response is well thought out, as is ShockMe (Ron)
NJ has a Lic Electrical Contractor and a Business Permit is REQUIRED to operate.
That said, there are also various 'low voltage' "titles" alarm (fire/burg), telephone "exempt card", etc. The Lic EC can 'do-it-all'. Some do, some don't. Our Board of Examiners also issues a 'Journeyman Card', although I have never seen one. It is not valid to perform work for hire (contracting)
As to the commentary; yse, I know resi guys that can get lost in a retail store job, and I know comm/ind guys that can't do 'house work', unless it's pipe. As Ron said, trouble and rework in old houses (fish, etc) is another animal, that craft comes from patience and EXPERIENCE.
John