Malcolm in the middle was always excellent for showing exaggerated examples of realistic family meals. For breakfast the kids are all eating some kind of sugary cereal and maybe some orange juice and dad is running as fast as he can to grab coffee and go burning himself in the process. Or on the occasion they make a nice weekend breakfast, the older boys grab most of the food and there's almost nothing left for Dewey. If that show could manage to come up with a multitude of family meal scenarios over the course of the show, why can't people writing movie scripts write one single semi-realistic scene? This trope bugs me just as much as hanging up without concluding the call.
I've made the full switch from thinking that hanging up without an extended goodbye ritual was weird, to embracing it. In business calls especially, the conversation has ended, and we've concluded the planning for the next conversation. It's past time to hang up.
I remember seeing somewhere that they would actually eat on All In The Family to make it more realistic, and if you watch scenes of them doing it, it definitely worked.
This is part of a bigger movie trope which is basically "ain't nobody got time for that". You never see them lock the door behind themselves when leaving the house, or fumble to find their keys, or any of these small actions that are actually required in real life just gets skipped over during the editing unless there's a specific reason the audience needs to see it.