We used to have DSL through AT&T (6 mbps max speed) that had a 150G cap. For a long time we didn't even know there was a cap, but as more things became HD more data was used and we eventually started hitting it every month. They would tack on $10 for another 50G.
AT&T does have an unlimited option, but we chose to switch companies because of speed and price.
We live in town and changed to Charter cable (30+ mbps) internet a few months ago. No data or bandwith limits and cheaper too.
Where my mom lives, there are not many choices. She had satellite internet but it sucked. Lots of dropping connections in her area. Their local cable company charges out the nose because they know they are the best option. She uses a cell phone hotspot instead, but it does have limited data. She does not stream videos or anything else like that, so it isn't an issue for her.