[shard]

The reason is momentum. Switching to measuring flour by weight will require households to have both measuring cups and scales, require recipes to be rewritten, require cooks with an intuition based on volume to relearn the intuition based on weight. None of this is insurmountable, just like none of the reasons for switching from imperial to metric are insurmountable, but for people getting things done, it's not enough of an issue to worth making the switch, so this kind of switch would require an institution or coalition with enough clout to make the switch and pull everyone else along. For cooking, I don't believe such an institution or coalition exists.