Sami, your link to that Indiana page was ok - until it got to the part where it said that they would 'make good' the sale. Yes, they used to do that, but it got so bad that now they are making the seller pay for it. That is the difference - and the problem. The rules for "Visa" were posted...
I think that part of the problem here is that the so called 'merchant agreement' needs to be revised. When it was drawn up they weren't thinking about card fraud getting as large as it is today. If a card is not signed, I'd have a pair of scissors handy and give it a good whack. They can...