No, you haven't. Just cause someone lives in the same building as you doesn't mean you are obligated to be buddy buddy. I lived in 5 different apartments over the last 8 years from Crown Heights to the UES. I don't know what NYC you live in, but where I was, nobody was really on the shyt you are claiming is normal. Only buddy buddy people were the ones who lived in a building for decades.... all the young people, for the most part, kept to themselves
If there were going to be "targets" and discomfort with separate entrances, there would be targets/discomfort with a shared one. We can talk about rich people being snobs and all that horseshyt but at the end of the day there are real correlations between various undesirable quality of life and safety issues and poor people, and it's not at all unreasonable to not want to come in contact with those elements (even though those elements aren't caused by all poor people). And no matter how much you try and force it, people from different classes don't mix naturally/easily. People relate to people like them and that's not a bad or prejudiced thing.
Ummmmm, a good way to do that is to keep poor people in the cities they are employed, rather than to displace them and force them to potentially face homelessness starting over. Don't be dumb and put pride before practicality. Poor people getting brand new apartments in safe neighborhoods is a good thing, period.