U.S. consumers aren’t just frustrated with high prices. They’re angry and confused about the increasingly high-tech ways that restaurant chains and major retailers are setting those prices.Digital price tags are rapidly replacing paper ones in grocery aisles. Artificial intelligence tools help businesses decide what to charge by predicting how customers might respond. Terms like “dynamic pricing” and “surveillance pricing” are stirring anxiety on social media, where users wonder if different people are getting different prices for the same product. Americans have grown accustomed to changing prices when booking flights, hotel rooms and rides, but the prospect of everyday spending shaped...