Onstage at D9, AT&T Mobility CEO Ralph de la Vega, plugging their upcoming mega-merger with T-Mobile, repeats his assuring line that wireless costs have dropped by 50 percent in the last 10 years despite tons of industry mergers.

Walt Mossberg appropriately snarks, "So you must have been way overcharging four or five years ago." De La Vega's retort is that data prices drop every generation.

So how come AT&T is effectively charging more for data today than it was a couple years ago? If I use the exact same amount of data next year, my bill should be lower, right? Right? [All Things D]