That's not what redlining means. Redlining is when you discriminate against people based on where they live (or in where your loan will let them live), not on who they live with.
> Redlining is when you discriminate against people based on where they live
Reread the comment. It's exactly what you describe, down to the actual building. People living in a particular apartment complex can't get a credit card.
Why do you think banks deny credit for areas? Because they don't like the geographical layout? Because that river throws off their feng shui? Or is it because a large number of people living nearby have defaulted or are predicted to default on a loan?