In Oregon all construction contractors (and home inspectors, and locksmiths) have a license, and must display the license number on their work vehicles and in advertising. There's a contractor website that lets you search by their license number to verify they're current, that there's no history of complaints, and that they're bonded/insured. They get to hold themselves as "Oregon Certified" in their craft, and of course, are penalized for operating a business without said license.
It sounds like the way the law was written for engineers was different than contractors.