So you both thinks it's OK to hold everyone up so you can have your car seat brought out for your "free" seat.
Do you both thinks it's OK to put you child in the back of a pickup truck like a dog?
Do you drive in your car without a carseat?
An airplane is moving a lot faster than a car does. An airplane can hit some pretty severe turbulance, I once saw a 250 lb person hit the ceiling on a 777.