I have two young children and they have been on many flights, longhaul and shorthaul, not once do my children get out of their seat unless they need to use the washroom, I ensure they dont kick the seat in front and always clean up after ourselves. If I tell them to put on their seatbelt I expect them to do so, which they do of course. It makes me mad when these pax feel its ok for their child not to be strapped in because they are asleep or having a tantrum.
It feels good when you ask them if they would allow their children to travel in a car going along at 150 miles per hour + not properly secured in their seats, with their seatbelts fastened.