That's still quite some decent margin. It takes about 5 minutes for me to fill my 40L tank, which would be about 1€. Everything is automated, there is absolutely no human involved, and it works 24/24.
There are extreme construction costs for petrol stations. It's highly regulated due to the fire risk and other issues. You can't even lead surface water into the gutter without prior filtering.
https://www.abwasser-analysezentrum.de/branchenuebersicht/mi...