Are wireless broadband providers really that constrained?

Verizon has a 5GB "soft limit" (in that they can go after you if you exceed it routinely) per month on their "unlimited" evdo broadband cards. Sprint doesn't have such a limit, but can still disconnect or warn you for "excessive" usage. Neither company wants you to use their wireless evdo cards as a substitute for a landline DSL/cable modem or for p2p downloading, watching internet television for long periods, and so on.

Is their bandwidth really that constrained? Or is this just an attempt to extort more money from "power users"? It seems odd that they would spend $billions building such an advanced data network, only to cripple it with so many restrictions. 5GB a month? I can go through that in a *week*. Not to mention the connection is $60 a *month*, which is much more than most land-line based connections.

These wireless cards must be a total godsend to those who travel a lot or are living in an area without cable or DSL; it's sad that the wireless providers cripple what you can do with them.