My Verizon device has been limited to 10GB per month, up from 5GB per month for an additional $30 per month on the bill. About a year ago it went from being a 3G type connection with a top speed of perhaps 768KB/s to a 4G device that at one point clocked against an unloaded tower for nearly 20MB/s down. (Actual usage is far lower, perhaps 8-10MB/s due to tower congestion).
Needless to say the most I can do with it beyond browsing forums and checking my email is playing MMORPGs. It can only barely handle TF2 or Minecraft for any length of time without making a major spike in my quota and risking going over, and a couple of months now I've ended up going significantly over.
Although Verizon Wireless doesn't implement a hard cap like Hughesnet did, their price scale for overages makes it potentially painful to go more than a few gigabytes over quota.
I can see where they would look at the user statistics and go "Ok this tiny group is using up almost all the bandwidth, lets punish them."
But the end result then gives the effect where they want people to buy the service and then not use it, actively punishing those that do with data caps and overages. The reason there is such a wide range of traffic patterns is because some people use the internet continually during the day, while other people barely get online at all. And these capping strategies do not take that into account at all when calculating limits.
Although at the same time, data caps themselves are not specific to end users.
Servers often have data caps as well, where they serve a role in allowing a provider to effectively provision equipment and connectivity to ensure that speeds are maintained under peak loads and that bandwidth is not being wasted by abusive users such as malware servers and bots.
As a hosting provider, I too provide some data caps. But in my case it is done entirely to discourage abusive users from signing up and for accountability purposes on my end- that way I know at the end of the month my server has sufficient bandwidth assigned that if everyone on it uses their maximum the server does not exceed its own limit. Most of the time if a user actually hits the cap I'll raise it for them as long as the statistics show they are using it legitimately.