Well let's see, I built my own home, do all my own mechanical work, and installed a sprinkler system at the age of 16 that still works fine. Irrigation is not complex and even a teenager can learn how to do it. When that same sprinkler system runs the sidewalks and street remain dry, and no dead spots appear in the lawn. My dad and I even pounded in the well ourselves with a tripod made from 2 x 4's and a stack of weights on a bar! Most of the contractors I see have low-paid, low skill labor doing the work anyway. You do not need years of training to run a trencher, glue pipes and screw in heads. Simple math and common sense along with a piece of paper is all that is necessary to lay out a good system. Are you guys using multivariable calculus to calculate flow? Are you even using bernoulli's equation to calculate pressure drops? I think not. Licensing is just to limit competition, plain and simple. If the quality of work really mattered you would not see homes with plumbing problems, roof problems or being damaged by storms or termites.