That's just life, we have cultures, we have in-groups and that's how the system works. But we do have a choice nowadays so (for example) the reason why you don't have white/black/etc. friends is on YOU for not being open minded and your ignorance.
We tend to link up with the people we relate to, people from our social class and that happen to be our race. Half the time it is without intention, it just happens naturally. It's about who you're comfortable with until you're ready to find relationships outside your own race (and that friendship will build naturally).
Especially when you consider that many of the people who live their are immigrants, and maybe long for a place where they can be surrounded by their culture.
Yeah.
Associating with people of a similar background provides a support system based around a shared experience. It isn't bad.
The reason whites see blacks as an outgroup and vice versa has racial undertones.
But its not. A black person won't likely see eye to eye on everything a white person has in general. There isn't a rule saying blacks can't associate with whites in the group. It all happens subconsciously.
Conversely speaking, I am what is known as an "only one." Meaning the only one who's black in a group of completely, or predominately white counterparts. It's been that way since elementary school, through my university days and most of the time has carried over into my professional life.
It's just a part of life for me now, but it is a unique and sometimes disheartening/humbling experience. I am more enlightened from this experience each and every day.
I used to live in a City that was predominantly African American and I remember people always talking about how it used to be around 95% White only around 30 years ago and that the "whites left" due to the influx of African Americans. Right now, it's around 60% black and only 35% white.