Caps are like speed cameras. They take a measurement of how fast people move through a given area, then lower the speed limit to what 30% of people actually travel and set up a speed camera 50 yards from where the speed limit drops down to the new lower limit and Bingo, instant cash cow on 70% of commuters.
Same with Verizon; set people on blisteringly fast FIOS, once the market has been thoroughly saturated, set a cap to the lowest margin of what your subscribers typically use and then impose data caps and overages while encouraging everyone to switch to your 4G LTE plan so you can take "Broadband as fast as your home, everywhere you go" which also has data caps.
*Sent from my unlimited 3/1 DSL line for $40/mo, which sadly is slower than my StraightTalk phone *
"My weakness is that I care too much"