I believe I've driven through Zion. It's small, and rural, IIRC. It's not unusual for low-density areas to have supermarkets scattered. I live in O'Fallon (pop about 30K), and there are 4 supermarkets within 5 miles of me. Contrast that to 1 in East St. Louis (and none in Cerntreville, Alorton, Brooklyn, Fairmont City, Washington Park), with ESL having a larger populaiton just by itself.
There were plenty of bars and liquor stores much closer.