Man, I wish I could go to the gas station and say "you're charging too much, so I'll only pay $3 a gallon....or I'll buy 10 gallons and steal 2"
That would be nice and all, but what about this scenario.
You go to fill up your car with $30. You want to use some of that $30 in your portable gas tank, but the station wants a $20 fee to be able to do that. I believe in that case one should hide behind their car and fill up the portable without the station knowing and be on their merry way.
Just so you know you should not play the analogy game as you totally s*ck at it.