most just figure when you’re 18 you can finally decide for yourself without beeing influenced by others, which is shit of course
just because you can drive a car and drink beer you wont have any more control over yourself and your actions than before – they just see it as a good age to “start” allowing it as 14 would be too young and 30 too old by most definitions. afaik and believe noone would charge two consenting adults who harmed each other if they did that in free will of the one harmed (more people..one way harming.etc too this was ju7st an example.)
abuse is only happening when someone is either harmed without his consent or is not in the position to decide with a clear mind for himself at the moment of the consent – might it be out of drug influence or age, or whatever.
but its that uncertainity that keeps bdsm underground..
if it was clearly forbidden by law you wouldnt find clubs for it, if it was clearly ruled legal we wouldnt have this discussion now
in germany its legal as long as consenting adults carry it out but im not 100% certain there