Last summer I fell over and my right seatstay cracked where it hit the curb, with my not insubstantial mass driving the impact. The seatstay did not shatter, and the frame was perfectly repairable and was not tossed. The shop cut out and replaced about 200mm of seatstay with a hand-formed section shaped into the correct curve and charged me 300 USD. Much more expensive than a repair of a steel frame, but certainly not impractical. I can't comment on the relative cost of a repair to an aluminium or titanium frame.
I appreciate that it's more difficult to recycle a totaled CF frame (or body panel) than an aluminium or steel one, but a crack or gouge does not typically damage a frame beyond repair.