We often take for granted that any professional who charges us money is appropriately trained, whether licensed or not. Perhaps we assume this because the plumbing field has been developing for over 700 years, and the licensing process looks almost the same as it did 200 years ago. But the plumber who walks in your door today may not be effectively trained, or may even do unsafe work. You probably won’t know it, though; most have learned to bluff through their work, and don’t believe they need to learn more.