> What harm can unethical application music therapy cause?

For that matter, what about retail clerks? They could defraud their customers or steal from their employers. We could license them too. Farmers workers could contaminate food. So could restaurant workers. Janitors who fail to clean properly could allow disease to spread. Groundskeepers operate dangerous equipment. News reporters could misreport the news. Priests could give bad advice -- or worse. To say nothing of legislators.

Just about anyone could screw up their job with severe consequences. So why do we license the people who cut your hair but not the people who make your food? It makes no sense. And before you conclude that the answer should be that we license people who make food, consider the consequences for people who would no longer be able to afford food. (Or a medical care, or legal services, or to have a working toilet.)

The more important something is, the more important it is that we don't price people out of being able to afford it.