The Mom & Pop Shop

Yesterday when I was driving to the Target on La Cienega and Rodeo and I was noticing all the independent shops that line the streets of South Central.  Then I remembered the funny Seinfeld episode when Kramer makes a valiant effort to try and save the mom & pop shoe shop, but accidentally ends up shutting them down permanently.  How is it people always say how hard it is to keep mom and pop shops open, but they're everywhere in the ghetto?  There's a 99cent store here, or Garcia's Barbershop there.  This is what I was pondering as I was driving to one of the biggest chain of superstores.  Please, someone explain this to me.