i called the the fuel retailer and was told that they would only sell 100 Octane Low Lead to be pumped into an aircraft, not a drum or 20 liter can.
I wonder if that's a California thing? Around here, many of the GA airports are "open" and pumps are self-serve. If you can find someone that's a pilot, they may be able to help you. It's "unreasonable" not to allow fuel to be pumped into containers - what if I'm a mechanic or I'm if I'm stuck at another airport where the fuel pump is out and don't have enough fuel to take off?
Some airports (larger GA) have "fuel retailers" - they are not self service and they pump your fuel for you (for a higher price) - I wonder if that's what you're running into. They won't want to pump small amounts.