I have been grooming for over 10 years, learned through several hands on programs and opportunities, not in a school. A lot of people who go to grooming schools have no concept of what the industry is like, and get in over their heads. I worked under the woman who trained me for 6 years, learning the entire time. I now compete in grooming competitions as well.
Plain and simple, licensing is necessary. I hate reading stories of pets injured by 'groomers' who lie about certification (a certificate of completion from a school is NOT certification, or licensing!) I agree that something DOES NEED to be put in place. There are efforts out there in the works in several states to create a licensing program similar to that which human hairstylists and cosmetologists are required to take. The hang up is noone can agree on who should make what rules, who should be in charge, and the list goes on. A board should comprise of not only groomers but also at least one veterinarian, and ideally an animal trainer/behaviorist. One giant lack in grooming is groomers don't always take the time to learn any training or behavior management skills (and it's scary that this doesn't just go for the dogs in all cases!)
Going to a school, whether reputable or otherwise, also does not mean you are 'instant groomer'. You may know some basics, but I see groomers all the time who stop there. A big problem that feeds this are big chains that provide 'grooming' services with in house trained groomers. They claim their groomers are 'certified' after taking multiple choice quizzes and reading a book. Heck, the one I worked for, the salon manager even gave me the answer sheet. Fortunately that's not where I was taught.
But anyway. I'll rest. The plain simple fact is regulation IS needed, and this is coming straight from a groomer, who is tired of the BS in the industry. I'm not perfect, never will be, but there's always something new to learn, you just have to have the drive and aptitude to BE a good groomer to take the steps necessary to become one.