I find the concept of pets on flights really bewildering. Is this entirely an american thing, because I fly relatively often and I have never seen anyone bring

I find the concept of pets on flights really bewildering. Is this entirely an american thing, because I fly relatively often and I have never seen anyone bring an animal on a plane. We don't let pets in a vast majority of indoor venues, so why should planes be an exception? I just think bringing a "comfort pet" on a flight is very childish and extremely inconsiderate not only to the rest of the passengers on the plane but to the animal itself as well. I've even seen videos of people with dog allergies getting kicked out of a flight because of a person with a comfort dog, which to me is beyond absurd.