I'm Thai. And there is Spanish R in my language, but I cannot pronounce it at all. So do many of Thai ppl (but not the majority). Some conservative people even look down to people who can't pronounce the R which is ****ing idiot.
IDK really. I'm Puerto Rican, but didn't learn Spanish growing up, which would obviously make it easy for me. But I learned my numbers and the alphabet in Spanish when I was young(like 6-7), so that's probably when I learned how to do it. So I guess it's kinda weird when people say they can't do it, when I've been doing it for almost as long as I remember.