MagMile
Policy is set by individual airlines on child ticketing fares and are not federally regulated. Because it is a "selling feature" most airlines have the same or a similar policy to be competative.
As to the last portion of your post...shame on you. As a member of this board you should have the aviation corporate strategy figured out by now. Airlines are much more interested in appeasing or accomodating the frequent business traveller...not the family of four/five/six that will take one or two vacations together per year. The company vision, no matter which airline in operation, is to get the best buck for every seat and that is how the revenue per seat, per mile is calculated. The unknown factor of how many children, potentially discounted, per flight would soon throw the standard formulas out the window and send general ticket prices soaring so that a conservative buffer could be built into every ticket sold.
Can you imagine what a fare from anywhere in North America to Orlando (for eg.)would cost if there was a discounted fare structure for children? A popular destination would all of a sudden become a money loser as there is often more children than adults on board this flight. It's one of the consequences of opting to have a family...you pay for travel of each addition you beget and as you chose to expand your family. Other singular, adult travellers would have to subsidize the fare that could have been realized in place of a discounted child fare occupying the same seat by paying higher fares so that the operating/profit margin expectations of the airline are maintained.
It might not sound fair to you but I feel comfortable stating that drastic change to this policy will not be realized or considered for the reasons I've outlined.
To take this to the other extreme...are large or overweight people charged more for occupying the same seat that a 6 year old could occupy? Are seniors charged more or less? Age or size isn't a factor; it's just business; a body present occupying a seat available in the financial scheme of aviation structure.
I shall await your rebuttal with interest.