Way more than USA use ANSI, there is most of Asia, Russia, Czech, Romania, Turkey, Serbia, Slovakia, Georgia, Poland, Netherlands, Arabic, Hebrew. Some of those also have ISO variants. I think the majority of non Latin based languages except Japanese use US ANSI. But still we have the problem with legends.
Flat profile is the easiest answer for reducing different keys with legends, but I think it is much less pleasant to type on.