If I could just add this, there are actually some good instances where varying interchange makes sense, in my experience. I don't know if you have government travel cards when you travel. You don't have government travel cards? Okay, I used to work on the issuing side in that particular space. It used to be that Diners Club and American Express had a lock on the market, and when Visa and MasterCard introduced different interchange rates for those particular products they allowed issuers to compete against Amex and Diners Club in that particular space.
Then in some cases, not here yet in Canada, although I would argue it would be a good thing, when merchants pass additional data along, as with purchasing cards—I think you have a purchasing card program—that additional data helps companies streamline their costs. There are arguments for tiering interchange to incent merchants to do that.
So it's not as though a more complex interchange system is inherently bad, although overall it has made our lives a lot more complex.