T-Mobile does this? I use my phone a LOT with them and haven't noticed any throttling.
It might be that you don't use as much data as you think. I use my phone for data stuff all day long, but don't stream music or video, and it's the rare month I go over a gigabyte. Apparently perusing stock prices and weather reports doesn't use all that much. However, on a recent motorcycle trip in Canada it hit some limit and got throttled. Non-https would work if I was really patient. Apple Maps worked okay, if slowly. Google Maps: don't even bother.
EDIT: I got it wrong. I got throttled because a 3rd-party contractor dug up Frontier's FioS lines, so I used my phone as the house hotspot on a 5Gb plan. Then we tried to watch something on the Apple TV. In HD. Oopsie. Upgraded to unlimited high-speed data after that. The Canada thing was T-Mo's "unlimited data in select countries". Problem there is that high-speed is quite tiny (200Mb?), then it's throttled. They'll sell you an international roaming pass for a reasonable price, though.
> Up to 3 GB of 4G LTE data. Speeds reduced after 3 GB. No overage fees.