That's true on every network except Three. Unlimited data on Three genuinely does mean unlimited without any restrictions (well, one actually, data used tethering your phone as a wifi hotspot isn't included). You could download a terabyte of stuff for £20/month (about $25).
For $125/month I have 4 family members on an "unlimited data" plan from T-Mobile (really that's 13Gb regular data, unlimited Netflix and other streaming).
I did buy all the phones outright though, which was $2200 upfront.
Don't forget that wireless is a scarce resource. I know that current mobile plans could be improved a lot, and the tricks that were invented to dance around the Shannon Limit are amazing. However, those tricks only push back the inevitable: there just isn't enough bandwidth.
EDIT: this one https://www.oister.dk/mobilabonnement/taletidsabonnementer/o... and then I took advantage of a "double your data" offering they had. It's 120DKK for 20GB, usually.