Australia has had data caps since broadband first came out; for the vast majority of of users a basic plan provides all the data they need, techy users with heavy usage patterns get higher plans, and people with the compulsion to torrent every TV in existence get plans with unmetered periods (a few ISPs don't meter traffic during the quiet periods at night)
The usual behavior once you're over your data cap is to drop the internet speed down to ~64kbs for the rest of the month so even if you kill your data cap you can still access email and other low bandwidth services, you're not off completely.