Wow, lots of choices. Maybe I’ve just been oblivious but I’m not aware of any E15 being offered here in Texas. Maybe it’s just offered in the northern climates?
The arrangement I described is not widespread. I bought the Ranger brand new; didn’t see an E85 pump for about 15 years. However, I have only ever seen E85 and E15 in an arrangement like that. Never as an outright substitute for the usual three blends of E10.