Exactly why not, over any other credit/debit card service? I get that you don't trust anything other than cash (or so it seems from your other replies) but Square is fine. Put away the tinfoil hat and gives us something good. I have a friend that uses it quite a bit without any issues. I have a square account, but haven't actually used it yet. I have no reservations about using it though, I just haven't had a situation arise where I've needed it. The flatfish has spoken! It must be fine, if flounder likes it! Seriously though, it's free other than the percentage, which you could split with the other person.