In the UK this is simply not the case. I have unlimited 4g connection, and I had unlimited 3g before that. In fact, the 3g was my _only_ internet for a long time via tethering. It was good enough to play TF2, and could easily download 20gig games overnight via steam etc.
I assume somewhere there is a fair use policy - but if i've never hit it I reckon it's doing a pretty good job of only hitting abusive use.
5g isn't going to solve the problem of US pricing being shit.