I think maxhou is referring to the segment of the network from Comcast's (or any other ISP's) local data center to its box (I think they're called ATM switches) and eventually your house
Yes; so what? The traffic always has to travel over that segment, regardless of whether the ISP is working with transit networks or not. So whatever the difference supposedly is between Comcast and all the other ISPs, it isn't that. So what is the difference?
The difference is how Comcast interprets its competitive position compared to its peers. The barriers to entry in the last mile is high regardless of the ISP but it is willing to leverage/extract rents/push the boundaries more compared to others that may be building goodwill/not push the regulatory boundary/sitting and waiting.
In other words it is acting like a monopolist or a shrewd business.
In other words, there is no technical reason why it's any harder for Comcast to "route traffic to the customer's house" using the same arrangement as other ISPs. The reason it doesn't is that it's trying to get paid twice for the same traffic, which is a "business" reason (at least for some value of "business"), not a technical reason.