I filled my tank on my old Saab 99 with Diesel accidentally once.
It was a different world then - The station owner handed me a garden hose and I stuck it in the tank and drained the gas into the storm drain on the busy suburban street. Never gave it a second thought. Nobody else driving through and pumping gas did either.
I remember when people changed their own oil, then dumped the old oil down storm drains.
I filled my '76 300D Mercedes (diesel) with regular gas once. In a hurry. Strange gas station.