If resident in a certain area don't allow mixed-use areas, its because the voters in those places don't want it. If the voters in 'anytown, USA' wanted a mixed use district - they would have it. Obviously it is not what most people want.
I know I don't want it, and would vote against in it my area. Who wants to buy a house in some quiet area and then have a combo 7-11/gas station popup across the street so that some huge corporation and make just a bit more money at the expense of a nice quiet residential area being destroyed?