> I wish at least one commercial airline would adopt a "pet-friendly" policy and just allow people to purchase an extra seat for their dog.

Depending on the size, you often can. I do this with my cat. He counts as my carry-on and I don't get any extra carry-on allowance for buying a second seat though. So there are some extra luggage costs involved in addition to the pet fee. But when the flight attendant comes by and says "sir, you need to put the cat underneath", I say "I bought this seat for him and the ticket agent said it would be ok." Hasn't failed me yet.