As far as 'Perfection' is concerned, it is unreasonable to expect people who have lived their entire lives in a different culture, would jettison it all and assimilate immediately? Some embrace their new found refuge more easily and rapidly than others...that's just a fact of life. Personally, I've lived in two environments (NYC and the CA Bay Area) that are highly diverse...and successful because of it. A hallmark of those successes is a 'culture' of Acceptance and Welcoming. It can be done...it SHOULD be done...Everywhere.