There's no doubt that mobile point-of-sale (mPOS) hardware and software has been disruptive to the payments industry. It's not uncommon to see cashiers swipe cards through a credit-card reader attached to an iPad or a smartphone at a coffee shop. But after analyzing survey data and talking to small businesses in New York City, we think that mPOS solutions from companies like Square and ShopKeep are not yet as common as reports suggest.