It's all in the terminology. Comcast does not have a charge for a digital set top box. They have a charge for an additional digital outlet. That charge includes the set top box rental. If you use a TiVo instead, you get a $2.50 credit for using your own box. In either case you are charged $9-10 for the outlet. Do you expect that if you use a Tivo you should get the $2.50 credit against no charge for the outlet?