I would add that we have many more larger EVs (with larger batteries) than EU does. Not too many Lightnings over there and not many ID.3 and Citroen's, E208s, etc over here.
However, I think it's going to take a while before we see non-Tesla EVs at Superchargers in droves, judging by what I'm reading over on the Mach-E forum. Maybe by the Summer... May/June seem to be what most earlier orders are getting with some already going to August, or later:
NACS Adapter Now Available + Ford EV Owners Can Now Charge on Tesla Superchargers in U.S., Canada!