Interesting. But we have to be clear here: It‘s not only about QWERTZ vs QWERTY. Many countries still have ISO keyboard layout: a tall return key and the left shift key is short (according to https://en.wikipedia.org/wiki/QWERTY). The US keyboard is different: the return key is wide and not tall, and the left shift key is also wider. If you once got used to the US layout, it‘s annoying to use an ISO layout, because your pinkies have to move a little larger distance to hit return and left shift, if you know what I mean. :-)