There were other things people used gas for, or alternately kerosene. Lamps were still common, and there were camp stoves, to name two of the most common. Lead would clog up the works of these appliances. I remember "white gas" pumps as late as the seventies (lead imparted a red color on gas). People needed that information, and demanded it.
So more to protect the appliances than the people, I guess. I do remember when unleaded gas started. I accidently put some of it in my 63 Chevy Nova and it ran like crap. Had to put some additive into it to get it to run better.
Then why aren't they blue and orange? Orange and black were Phillips colors nationwide. And Bartlesville is less than a hundred miles from Stillwater. Sorry to burst your bubble...