Fair enough, that.
You don't get the last word by ending your post like that.
But yeah, saying "this is America" was just a cheeky way to say the standard usage in MLS and locally for people with that job is head coach. Which it is. Check any MLS team's website and the official listed title is head coach, not manager. Generally my position is to go with standard usage for the locale, because I'm not invested enough in my preference to do something that will just cause confusion. So I call Klopp, Pep and Mourinho managers, and Kreis, Tata and Bradley coaches. But when Bradley was in Swansea -- brief as it was -- he was a manager. Same way I list team records as Win-Lose-Draw in MLS but Win-Draw-Lose most anywhere else. Doing anything else is bad communication.
I also don't generally don't pick fights on usage, but here the context matters. If I see someone write or say "manager" for an MLS coach I know what they mean and so I don't care, but when someone uses non-standard usage in a thread title which makes it impossible to find the thread by searching for the actual official usage, I'll answer that it's not my fault that I couldn't find the thread to post there.