Can someone explain why Springfield is considered cheap to live in?

Every time someone tries to say something good about Springfield, they say, "Well, it's pretty cheap. The cost of living here is pretty low." Really? Can you explain how? I'm comparing it to St. Louis because that was my previous city, and I lived there longer than in Springfield. Also it's only 1.5 hour of drive so it's not like I'm comparing apples to oranges. I'm sorry to say this, but everything was cheaper in St. Louis—rent, taxes, gas prices, groceries, clothing, going out, etc. So how is Springfield considered cheap? Do people compare it to Chicago? Because if they do, that's unbelievably ridiculous.