The above is a screen grab of a new Verizon policy that is going into effect today (November 13th, 2014). It's a very small, yet sneaky new way for Big Red to "transition" customers away from the old school grandfathered unlimited data plans. Basically, anytime a customer is taking over an account from someone else, they will need to switch to one of Verizon's current data plans and give up unlimited data.
Obviously there are only a few corner cases where this is relevant, so it may not be worth getting worked up over, but it is basically par for the course for a company that probably wishes it never offered unlimited plans to begin with. Keep this new policy in mind if you are considering taking over someone else's account.