I think it's because Polish food stayed like it was in Poland and hasn't adapted to the American tastes. This 'Chinese' food is in reality Chinese-American in China they don't eat this stuff. Someone who's lived in Italy before told me he never saw this whole Italian water ice in Italy, or Italian sausage off the grill with onions.
What's Italian water ice? I know I've never heard (or seen in Italy) of Italian sausage being grilled with onions.
Funnily enough, I actually quite like the Polish interpretation of Chinese food - yes, even including the obligatory surowki. It can be a bit strange sometimes, but on the whole, it's actually not bad.
Here's one place in Philly that is right downtown, keeps regular evening hours and has very good food:
But hardly any of it is actually Polish. I don't recall ever seeing "Russian Crepes" (!), "Austrian Lamb Stew" (Lamb? In Poland?), "Norwegian Strudel" (err) or "Borscht" (.....seriously, A 'Polish' place calling it that?) on a menu in a traditional Polish restaurant here.
PennBoy is right - the food has stayed as it is, and for that reason, it'll never do well in America.