I saw on a website that DC charges about 2.8% to merchants while MC/VI charge about 1.6% Since MC/VI often give back 1% via rebates to customers, even they don't have to charge 1.6%, so why does DC charge 1% more, even more than AmEx? Because they can, or because they aren't as efficiently run as MC/VI? Does this mean the end of DC (charge cards or travel & entertainment cards) in the long run?

By the way, I am not a merchant just someone surfing around the internet and found out the rates charged to merchants. I also posted a similar thread in the AmEx page.