This is honestly a pretty ignorant take on america and its culture. A lot of our culture comes directly from the places people immigrated from, mixed with the culture that already existed. After a few generations it amalgamates into the broader culture. Its constantly evolving (whether people want it to or not). Its quite the opposite of only knowing culture fron our own country. In fact, a statement like that makes no sense when you factor in how peoole got here in the first place
Ok but if it’s integrated to your culture and seen as local culture but it actually comes from elsewhere and people don’t realize that US culture is just everyone else’s culture, it just shows that US people aren’t cultured since they just assume that everything is US culture when it’s in fact foreign.
There’s a reason why the “American calling black people African American while traveling abroad” cliche exist.