You basically just proved my point. E15 couldn't be sold during the summer due to its RVP. The war in Ukraine created the supply disruption, so an E15 waiver was issued on May to allow the higher RVP E15 to be sold through September 15. The waiver didn't allow higher RVP gasoline to be sold.

The BP fire [[and the earlier Delek failure) created localized shortages, so eastern Texas and the Lake Michigan states got emergency waivers to sell higher RVP gasoline.

Glad you finally sort of understand. Gasoline also has regional RVP limits even with zero ethanol [[E0).