at a restaurant, in a plane, in the train... it's so freagin annoying. The implied social contract that you use such devices with headphones go out of the way the moment there's "omg a kid so cute" involved.
And you know you can't ask them politely to turn off the sound, the kind of parent that allows their kid to do that won't take kindly to such requests because Jonny is special and he just NEEDS to watch YouTube right now.
Kill me.