U.S. airlines are changing the rules of their frequent-flyer programs and, befitting air travel, being greeted with a measure of rage. Amid strong travel demand, Delta and Southwest are now pricing loyalty awards more like all other tickets—“dynamically,” with regular changes in how many miles it takes to buy an award seat. It looks like United is next. That means the number of miles required for a ticket will vary with sales, destination, cost in dollars, and other factors. “This is likely to become the new norm on the award side of these loyalty programs,” says Tim Winship, editor of FrequentFlier.com. Get the full story at Bloomberg Business