Three "Unlimited" plans?

The Ting Mobile site currently shows 3 different plans called "Unlimited": "Unlimited 25" for $25, "Unlimited" for $45, and "Unlimited Pro" for $55. The 2 higher priced ones offer 22GB and 35GB respectively (with extra fees if you go over that…not unlimited), while the cheapest says "Unlimited High Speed Data". Am I dumb or is there some obvious difference I'm missing? Why would someone pay $20-30 more for non-unlimited data?