Schoolmedsboi, I think your question is an excellent one. I grew up in Cincinnati, with it's heavy German immigrant population. Every kid I knew with a German last name had gotten many appointments with a bulb syringe and most with the bag, also.
We also had a large number of Irish folks. It seems to me that even though enema bags were unheard of in Ireland, the Irish/American people soon found out about their virtues in the US and began using them.
The eastern European people we had also knew about bowel irrigation. The Jewish population also believed in frequent enemas. I don't recall Italian, Spanish, or other Europeans having a similar bent. Most of the black kids I knew had experience with enemas, as well.
My overall take on this is that some immigrants brought the practice with them and it spread to other American groups and it flourished here. So yes, I believe that enemas became an "art form" , in the US many decades ago. In talking with my grand parents and great grand folks, I learned that bowel irrigation was very popular in the 20's, 30's and probably before those times.
It's just one of the many American gifts to the world and especially to we "Klysmo's here"!