That's kind of unusual in this day and age, because most of the EPA Specs require a minimum of 10% Ethanol in Gasoline sold Retail, in all 50 states. Then they have 9 "Environmental Impact Cities" where a "Special formula Gasoline" is required, some at certain times during the year, some, year round.
I dunno about Idaho, but in most states that have highway taxes as part or all of the state gasoline tax, and sell both diesel and gasoline for "Off Road Use" and is colored differently than standard pump gas and has a distinct exhaust smell so that authorities can tell whether you're driving on the highway with Taxed Fuel.
The "Off Road Use" includes racing as well as construction equipment, farm use and other equipment that doesn't ever see a highway . . But here in Colorado, I dunno where you'd find "Pure Gasoline" other than Racing Fuel. When I was in the Construction Business, the State was pretty zealous about checking our Trucks and diesel pickups for "Red" Diesel. They want those taxes!