Large ISPs like Comcast are offering services over a variety of different systems -- some may not be upgraded or otherwise do not have the capacity available to

Large ISPs like Comcast are offering services over a variety of different systems -- some may not be upgraded or otherwise do not have the capacity available to support the 105Mbit/sec package. This $250 fee is probably to cover the instances where they do need to make backend changes to support faster speeds for the customer. They charge every customer the fee to spread the costs associated with that out.