They clearly have to some extent. That's why I mentioned the National Park Service trail. More would be better, for sure, but we don't deny it, nor prosecute people who say it happened.
That's an argument that the US could handle it better. My argument is simply that some countries handle it qualitatively better than others, and in particular that the US acknowledges and learns from the Trail of Tears in ways that Turkey does not with the Armenian Genocide. These two arguments are compatible.