The pay-by-phone crowd is growing at the checkout counter.
More consumers are using their smartphones to pay for goods and services, and more companies are offering "mobile-payments" or "mobile-wallet" services.
In addition to Apple Inc.'s Apple Pay, which launched in October 2014, the field includes Android Pay from Alphabet Inc.'s Google and Samsung Pay from Samsung Electronics Co. There's also CurrentC, a system being developed by a group of major retailers and restaurants.
Wal-Mart Stores Inc. last month outlined plans for its own service for shoppers to pay in its stores with any major credit card or its own gift card using the giant retailer's...