That plan causes a whole set of other problems when actually executed. First off, two big factors in the price of an apartment are location and amenities of the building. So you can't really build affordable and luxury units in the same building. What you end up with is luxury units and subsidized units. That is certainly a category of "affordable", but the result is a bunch of people will get angry sharing their building with other residents who are paying a fraction of the price for basically the same apartments.
Also not everyone who needs affordable housing is a working class family that is trying to pull themselves up by their bootstraps. You can get a lot of "less desirable" residents like current and recovering addicts or people with mental illnesses. They obviously deserve affordable housing, but you will find that plenty of people who buy luxury apartments don't want to share the elevator with them.
You can just check the Yelp reviews of any building that has a mix of luxury and subsidized housing to see examples of these issues. Buildings like this always attract bad reviews, suffer from high turnover, and therefore have low occupancy rates among their luxury units.
Also not everyone who needs affordable housing is a working class family that is trying to pull themselves up by their bootstraps. You can get a lot of "less desirable" residents like current and recovering addicts or people with mental illnesses. They obviously deserve affordable housing, but you will find that plenty of people who buy luxury apartments don't want to share the elevator with them.
You can just check the Yelp reviews of any building that has a mix of luxury and subsidized housing to see examples of these issues. Buildings like this always attract bad reviews, suffer from high turnover, and therefore have low occupancy rates among their luxury units.