This is a really long thread, and I'm jumping in late, so maybe this has already been covered.
I don't see the rip-of factor here. A few months ago, in a fit of laziness and "I'm in a hurry" I went to the orange box and exchanged an empty Blue Rhino tank for a full AmeriGas tank. It was clearly marked on the AmeriGas tank that the tar weight was 17 lbs but that the net weight was 15 lbs.
It doesn't matter whether the exchange cost me $15, $25 or $250, the tank was marked with the weight of the contents and it was my choice to buy it or not. How is the consumer getting ripped off if they have all the information they need to make a decision?
On the other hand, I just came back from BJ's where I got a Blue Rhino can filled for $13.99. I took it home and weigh it: 35 lbs. So obviously I got my full 17 lbs (and a better deal) at BJ's than at the orange box, but in both cases I knew what I was getting for my money.
Read the label, or the unit pricing info, and if you get what is stated for the price marked, you didn't get ripped off.