Mark, you are oversimplifying the market
1. All wireless networks are capped by spectrum capacity / physica. As a user, you have been on a congested cell site and a congested 802.11 AP. So, as an operator, you have to ration service. That means cap / qos / $
2. In the USA, Cable / fiber / copper ISPs sometimes do not sell unlimited either
Network operators like to set their rates based on some median user profile. They are not being exploitive. Some users tax the network more and drive the upgrade cycle more than others.
3. There are wifi providers, wisps, cable, mno ... they all compete and blur the lines. I think wifi has provided limited benefit to cable operators that have deployed it, but hope for using free spectrum springs enternal