Part of it is because some large companies buy their fuel months ahead of time and have a filling station where they fill the tanks or trucks, airplanes, busses. etc.
So, they spent 4.20 on gas and still have 40% of that fuel in the tanks that they need to remove but can't take a loss on the fuel.
It's not the same with every company, but the shipping companies i know that deliver to the airports store the fuel at the airports. The airlines bought the fuel months ago and since the amount of shipped goods dropped, and the amount of travelers dropped, they still have the expencive fuel sitting in their tanks.
Just what i have seen, by no means is that every company.