Most people do not wish to be unkind to fellow humans. We usually try to be kind to other people, whatever the differences between ourselves. Here is what goes wrong, in the USA and elsewhere. People with similar characteristics tend to associate with each other. We cannot prevent this.
Freedom of association is an important freedom in any democracy.
In the Czech Republic, Gypsies may choose to live close together. In the USA, blacks, Hispanics, and other ethnic groups often seek to live in neighborhoods with their own. Living apart eventually causes problems, since politics eventually intervenes. Groups of people who are different and isolate themselves are eventually regarded with some suspicions. It is easier to use racial tactics like this than solve the real underlying problems.