Let me make it clear what firefox should do (and does on my computer one the stupid Comcast thing is fixed).
1) I type "www.amazon.com" I am brought to the amazon.com website no search pane no advertisements and no extra clicks. (Even comcast gets this one right).
2) I type "amazon" (missing the ".com" part) I am brought directly to the amazon.com website. No advertisements and no extra clicks.
3) If I type "amazon.co" I am brought directly to the amazon.com website.
4) I type "able2know" I am brought directly to the able2know.org website.
5) I type "www.brahhhhts.com", I am brought to a Google search page (exactly the same as if I had typed "www.brahhhts.com" into the google search bar).
The fact is that I don't want to see a freakin' search page on any of the first 4 examples. 99% of the time I just want to go to the page I am thinking about and 99% of the time the page I want is absolutely obvious. If I want a search I will type into the search bar and the only other time I want a search is as a last resort.
But the real point is that I can configure this myself. Once Comcast stops hijacking the page not found code the behavior in each of situations is under my control. I can set it up however I like.
If you want a search page, you should be able to choose to have one (and I really doubt that if you had this choice you would choose Comcast. You use this Comcast search page because you are a somewhat captive audience.
Comcast is making it difficult for you to customize your own system because they want to sell advertisements.