Is AT&T really making $30/month from people's browsing histories? I suspect that data is worth dramatically less, so in a competitive market the premium for not being spied on ought to drop.
I think its better to look at this another way: that they are making $30/month from the privacy concerned and that the higher price would not hold as their only price if they got rid of the "privacy plan". $150/month seems comparable to what other companies charge for similar services, while $180/month for that same service seems high. To me this feels like a trick to get most users to opt in by artificially increasing the price of their "standard" plan.
It may not be a discount. The higher fee is to discourage the more expensive service. We're assuming that the baseline cost is the lower one, but what if it isn't?
