Integration does work but not when you segregate a minority into ghettos. The Germans learned this and they stopped segregating refugees. Everywhere else the refugees end up in a 'camp'.
Imagine a policewoman, from 2nd or 3rd generation of a guest worker family, considering herself to be "rather turkish". And actually that's a sign her of flawless integration - completely in line with the way how the "German" Germans think of her. Because she has dark eyes and slightly, really just a tiny bit darker skin, even if she behaves like a typical German police(wo)man.