this post goes farther than folks knowing/not knowing about Dom/Sub, so i apologize for taking it a bit off track.
i think the biggest barrier to people being rather open about their intimate & sexual fantasies or desires is that there are toooooooo many people in the USA that will condemn them in some way. tho' folks like mr. "grab em by the pussy" seemingly are immune to condemnation :^(.
and since most people wouldnt want to be condemned or publicly shamed, they wont share their fantasies or desires.
similar to being out in public (store, mall, park, restaurant, gym, etc.) and you see an attractive person, someone you would like to "get to know." it's rather difficult (even more so these days) to a) find out if they are interested in being physically & sexually intimate and b) actually get them to get physically & sexually intimate with you. so, we lust after folks. and then some of us satisfy that lust by visiting providers, asian spas, streetwalkers, legal brothels in nevada or other countries.
in my real world & hobby opinion, the usa is just too prudish to tolerate much less accept people having intimate and casual sex -and- being rather open about it.