Well they don't have to live there.
I've heard this line a lot from some people in my state. If you are from or talking about the US as part of that, 99% of us are descended from a mixture of refugees, poor immigrants, slaves, and colonists. Nobody "has" to live here.
The line always feels disingenuous, like a quick way to dismiss someone's problem. Someone who has mostly been in good health could tell a disabled person who loves their home and country that "if you don't like not being able to receive medical care here go somewhere else". The disabled person obviously doesn't want to live anywhere else though, they were born an American and they want to work towards helping US society to change. I think that's a lot more patriotic of them than running away to europe or africa or asia or wherever else.
There are states, including the one where I live, where the people are still severely segregated. I don't know where you live, but you have to go out and see it in person to understand if you're living in an egalitarian area where the whites and the few blacks all have it pretty good and live together with no problems. There are countless poor white towns where black people are seen as inherently suspicious. There are companies that on paper say they'll hire anyone but somehow have no "qualified" black people in an area that is mostly black because every black person just "isn't the right fit". There are cities where where you are born determines whether you are taught anything in school, whether you get basic munincipal services, and whether or not you live in a gang saturated hell hole, and the biggest predictor of where you are born is what race your grandparents were and what race you are.
Telling someone soft racism doesn't exist inside the corporations (which form the bedrock of every society), in their own personal daily interactions, or in the opportunities they are given just because you personally haven't seen it is probably some of the most disingenous bullshit I think I've ever heard, and it happens a lot both online and in real life. And telling a fellow American citizen who offers their own personal experience and their own opinion on it to "go somewhere else" is the most unamerican thing I've ever heard.