In my younger days I thought direct democracy was unworkable, but now I realise that might have just been my brain conforming to the bourgeois representative government status quo.
Obviously we easily have the tech to do DD these days, everyone has a smart phone in their pocket, we could do it instantly and on the go. But how you could manage a planned economy that way I’m not sure.
this is a common criticism, that it doesn't scale.
but you're using corporations (walmart) and their organisational structures to argue this, when those are not democratic organisations (not even representative democracy). So ofc they can't work with democracy, they didn't come from it.
the same goes for the problems of nations and resource distribution - at no point was the system of commodity trade & exchange created or agreed upon democratically, the same is true of nation states.
in fact i'd predict that under dd, national borders would naturally drastically change or disappear, and the resource exchange mechanism (the world economy) would become much better adapted to fairly solve the distribution issue.