Everyone is ok with being sold something that they understand, most people are not ok with being sold something that screams "UNLIMITED" and then uses fine print to limit your seemingly unlimited plan.

Maybe the plans you're describing could spin the feature as "throttled for your pleasure" or some such. I'm sure there are marketing people that can come up with a positive way to spin it that isn't a borderline falsehood.

If I throttle your car to 5mph, is the distance it travels unlimited?

Bandwidth is the same, if you set a speed limit, you are also setting a distance limit.

Only if you're maxing out all the time. I had a plan with a similar sort of thing, even after using up all my "fast" data I had enough bandwidth for regular browsing and streaming music.