I think it goes by population density.
Basically Zogger.
There's two uses of Ethanol.
The first is an oxygenator -- the role that MTBE used to play up here in New England, to make reduce harmful emissions.
As we know, oil and water don't mix. So it used to be cleaning up fuel tanks that leaked was relatively simple...since the petroleum products would float. MTBE was a water soluble carcinogen, so it's leaks contaminated the entire water table. And because tanks are used for different products, even stuff like heating oil would pickup residual MTBE contamination from previous loads of gasoline.
So after all the new cars were switched over to electronic fuel injection with computers reading oxygen sensors to determine the right fuel/air mixture and carbs were relegated to small engines and antiques, they decided to use a non-carcinogenic oxygenator called ethanol. Still contaminates water if it leaks. And isn't needed by 99.95% of the cars going up and down the road today as daily drivers. (In other words, it's pretty fracking useless today at addressing pollution because technology has rendered it obsolete for the vast majority of fuel usage).
The second is as a farm & agribusiness welfare program, and that's when you started seeing it even in areas that didn't have outdated air pollution control standards in place.