Lower cost of living makes possible economic modes that the already relatively high economic floor in St. Louis makes prohibitive. Plus, the relative benefit of pouring X dollars into an area with lower per capita gdp is much higher: going from 20 cents to $2.20 a day is a much bigger life change than from $10 to $12.

Still could be helpful, and I think we do see it often in some form or another, but is also subject to regulatory arbitrage: two cities pitted against each other to provide the best situation for companies, or Walmart flexing their power to get more favorable deals.