Both the above certainly are examples of people getting rewarded for flying, even though they are not the ones showing any loyalty. Neither has really "earned" the TP points, they sat on a seat that someone else paid for.

I wonder in the case of children, might a fairer system be that the ticket purchaser be given the option as to whether a particular flight accrues against his account or the account of the child. If would allow the loyalty to be more directly applied to the person showing the loyalty, and might for example, offer the opportunity to hit a lifetime gold or whatever, which would be a long term reward.