A price-per-MB that falls during the course of the month as you use more and more. Isn't this exactly the opposite of the way other metered services work? With

A price-per-MB that falls during the course of the month as you use more and more. Isn't this exactly the opposite of the way other metered services work? With residential electricity, for example, isn't it usual for the price per additional KWH to rise as one's monthly usage crosses the pricing tiers? Isn't that exactly what you would want to encourage people to moderate their use of a supposedly scarce resource (like energy or bandwidth)?