It's not always that easy. There's no easy choice between bored and tired child screeching because he/she/it is tired and bored, or screeching because he/she/it feels uncomfortable in headphones when changing altitude in a pressurised cabin, or playing a video on an ipad with audible audio.

I remember the short lived snoring thread where the answer to noise nuisance was something along the lines of "touch me and it's assault" followed by "it's public transport, innit". I think the initial response from most parents would be more conciliatory, but along the same lines ultimately. Personally in both situations I put the Bose headset on.