As much as I'm annoyed giving out my phone number at retail... I've got to admit, Square's "text me the receipt" thing feels like the future we should have. But it's a little bit odd that it needs an additional channel. Why couldn't the receipt data go through the payment provider, and show up as part of my bank statement? I realize the answer to this question is probably much, much more complicated than it sounds, but are there any real technical hurdles to implementing something like this?