The Real Reason for Bandwidth Caps+Dane Jasper
of Sonic.Net explains why he thinks bandwidth caps really exist: to prevent the development of an alternative to television:
"My opinion is that caps make little technical sense, and I believe that the fundamental reason for capping is to prevent disruption of the television entertainment business model that feeds the TV screens in most households....
"As of 2008, the Nielsen Co. says that the average American household consumes just over 8 hours per day of TV. To replace this with some sort of innovative and interesting new Over-The-Top offering, it would consume roughly 480 Gigabytes per month (based upon Netflix consumption at their current top “HD” rate.)
"Keep in mind that this is the normative household TV consumption, so roughly half of homes view more than this! Add in day-to-day Internet use and clearly the 150GB to 250GB caps which are typical today are an effective blockade."
The other thing Dane points out is that even if "bandwidth hogs" were indeed the problem, putting in data caps wouldn't solve the problem, since it's not total data usage that creates problems, it's peak time usage, and the people who cause peak-time problems are not necessarily the same as those who use a lot of data overall.
The piece is well worth a read, and includes a link to a study of Sonic's users that analyzes data usage and bottlenecks.