Your second example is actually really fascinating - backup and photo providers get awesome deals on bandwidth because that part of the circuit is typically highly underutilized. So, ironically, it's a case where backup providers argue that their circuits should be charged at much less than market rates because the traffic is going in the opposite direction ,and their provider usually has circuits going idle in that direction.

I'm willing to wager that backup providers haven't run into any upload issues with Comcast for this reason.