I wish it was like Texas over here. To get your license in my state in Aus you have to pass the 6 month course, and have 3 years field experience under a licensed irrigator (or plumber- they do not need a separate lic for irrigation). But then anyone can install or maintain an irrigation system which is why there are so many rubbish systems put in, mainly by landscapers. New developments will sometimes ask for a plan of the irrigation system and state that it must be installed by a licensed contractor and also give them as built drawings, but that is pretty rare. It's really just a free for all.
Good to hear the young bloke OP make the right decision to pass on the irrigation work.