Workman's safety if I understand correctly.
There are quite strict rules WRT HES in our place of the world. Initially, it seems ridiculous that simple jobs should require a professional diver's cert, but due to the large grey area, the rules are simple: If you're hired to do a job underwater (I believe, but am not sure, that DMs and instructors fall into a different category and that their DM/instructor certs are sufficient) you have to be a professional diver with the required qualifications. Seems unnecessarily strict, but protects the life and health of those who dive for a living. I can live with that.