OK, that's interesting. Seems counterintuitive to me, but I'll go with it as this is not an area in which I have a lot of knowledge.
I'm trying to find some specifications regarding how high a pump can lift a column of fluid, but I'm not sure that I'm searching the correct terms. The only thing I've found is for well jet pumps. Depending on the pump, they can lift water upwards 100 feet.
But no mater what, I'm really thinking that the amount of lift found in your average gas station is basically negligible.