That's a nice comment, good information.
But like, the reason he generalises is probably because of the massive destruction of indigenous American culture that was perpetuated by European colonialism.
Thus we are very ignorant of all of the cultures. Which saddens me greatly. (I love shows and movies which use the native languages and portray the cultures when they're actually done well. I wonder how right they got the Kanien'kéha language that they're supposedly speaking as Mohawks, you can hear some in This clip - weirdly to me it sounds sort of like garbled and nasal Estonian being spoken for some reason)
You make a perfectly reasonable comparison that people rarely generalise to such a degree when it comes to Europe. But had like 95% of the culture and people's been erased and forcefully surpressed, then I think people would generalise to an extent. Not that it makes it okay in any way, just saying that ignorance is the cause of such generalisations usually.
Which is why comments like yours are so great, bringing the info that we haven't found (or even looked for.)
So keep up the good work! Thanks