I know it’s anecdotal, but I have never heard anyone use the word “oberlander” outside of internet forums. I’ve met true Oberlanders and they either describe themselves as Heimish, Chassidishe (even when they aren’t), or Hungarian (even when they aren’t from within the boarders of modern Hungary).
DY:
I do not merit to understand how tachanun, which poskim make a point of saying is a reshus not a chiyuv, would take precedence over chazaras hashatz once you’re in the business of deleting stuff for bitul Torah. Even with the explanation you gave (which I’m sure is correct), how could that really apply in America? Unless the beis medrash had a “no aino buckis allowed” sign, there could always be someone who needs it.