Heh. Sure, we all want lower fees. BitFloor makes substantially less per transaction. It's their choice.
The amount made per transaction is independent of the principle of paying the liquidity provider. Mt.Gox make 0.65% * 2 per transaction. That can be split anywhere they like, and the percentage to provider can be anything they like. For example if the liquidity provider is paid 0.5%, then the liquidity taker has to pay that 0.5% plus the 1.3% trade fee = 1.8%. I'm not saying that would be good; but it's to demonstrate that paying the provider is a separate issue.
I know. But I'm talking about the numbers quoted above, not about the principle. The principle is basically the same between Bitfloor and Intersango now, but Bitfloor takes a much lesser fee and balances it more towards the liquidity provider.
The only thing I'd say is that they aren't the same because of that key threshold: zero. There is a huge difference between a trade earning you a fee and a trade costing you a fee.
I'd not heard of Bitfloor before your comment, but I will investigate them now.
Depending on the spread, the fee being in your favour might not mean much.
Many local currency exchanges work on "0% commission" but then give you horrible valuation and spreads, being A LOT more expensive in practice than a good exchange with competitive spreads and a 1% fee.
In fact Intersango worked without any fees for some time and often mtGox was the better deal to both buy and sell. However Intersango is very convenient for me having a British bank account and being able to trade in GBP. If I have to deal in dollars that involves some friction and some loses to currency swings. I might hedge that but I don't trade anywhere near enough to justify all this complexity.