What makes the martial arts more of a risk is that it is largely unregulated in the U.S. This means anyone can open a school. There are no background checks, no school licenses, nothing of that sort. Most other after-school activities have some requirements in place for anyone working with kids. But most martial arts schools just make up their own programs, often having their senior students serve as child-class instructors. Those students usually have no training beyond the curriculum of the school.