Receipts on site...not necessarily. The last few times I've been to the Apple store, I've been content to just pay for whatever I bought standing in the middle of the store, bag it and walk away with the receipt sent to my email. Paper is a hassle in some instances...more to keep up with. At least if the receipt's in my inbox (and I happen to need it), I can search for it without having to destroy my house to find it.

EDIT: Then again...I can see where wanting a receipt could be valid--to make sure you're not getting ripped off. Makes me think of the sign next to registers in most fast food joints: "Call 1-800-whatever if you didn't receive a receipt and get a free order of fries." I'd still go receiptless, though, for places I know to be absolutely legit.

I never want a receipt. It's a waste of paper; I always throw it away right away. When will a receipt for a cup of coffee come in handy? All my credit card transactions are documented by the bank anyway.

Receipts are up there with cashiers giving me a bag for a single item I can easily carry.

If at a business where a receipt is important, it's easy enough to place a wifi receipt-printer nearby.

(I'd be very surprised if the main use of Squareup was "paying back friends".)