I've taken a pet along on a trip in the cabin in the not too distant past on CO. I am very grateful that CO permits this, but I side with you: I think the cost is extremely high. Sure, I can understand charging "something" as an insurance policy or the like, but $190/RT for what is virtually indistinguishable from a legal, carry-on bag is all but larcenous in my opinion. My pet did not make a peep. Aside from the specially-made ventilated bag, no one would otherwise know that I even have a pet therein. To the OP who posed the question, "why does CO charge so much?", I'd hazard the guess: simply because they can.