I cook every meal, and I can tell you, food prices are starting to look iffy to me. I can only imagine someone on a fixed/restricted income. Let alone having a spouse or a kid or two.
I also think you over estimate the average person's ability to save, even if you're not buying a bunch of extravagant crap. In the "middle class" there isn't as much spending going on as people think.
Also, sure you may be able to buy that type of home in Detroit for that little (which i argue really isn't that little... especially if you have no savings and shot credit), but if it's in the city proper, you have increased food costs, lack of public transportation, deficient police, fire and ems, high taxes as Detroit tries to recoup loses... etc. If you live in the suburbs (which most people do in Detroit, which eroded their tax base and caused their current problems), you have the issues I highlighted above.
Combine that with little job mobility and lack of a viable path to increase income... the "middle class" is taken for a ride... the poor are screwed.
God forbid you have student loans.
We need to do better as a society.