“Some locations…”There are plenty of "adventure hobbies" that are treated just like scuba in the US. Skateboarding, kite boarding, rock climbing, mountain biking, road cycling, etc. Some locations have laws & regulations as to where and sometimes how they are conducted, but the hobby itself is not regulated. Why should it be? I don't need the government to protect me from myself. I do not care to live in a nanny state. I take the risks, I bear the responsibilities as to the potential outcomes.
I’ve never heard of a skateboarding certification, or a kiteboarding certification, or a rock climbing certification, or a mountain biking certification, or a road cycling certification?
Yet SCUBA certification exists, and to the tune of a very pretty penny for most of your average people.