It's not the stand they make money on, it's the 2.75% payment processing rate. That is higher than what competitors charge (closer to 2%), and as business grows

It's not the stand they make money on, it's the 2.75% payment processing rate. That is higher than what competitors charge (closer to 2%), and as business grows that can add up to a significant premium. That is what drives them off of Square. So there's a kind of glass ceiling there.. to keep those customers Square would need to renegotiate a lower rate that trims down their gross margin. Square does have a really good niche in the mom-and-pop shops where 2.75% is an ok price given the easy of signup and free POS system. But at the same time there may be significant customer acquisition and support and fraud costs in that niche.