If the plug is loose and you grab and yank it, there’s no risk of touching the hot, and the ground won’t hurt you. Also, with ground side down, loose outlets expose the hot connection when gravity pulls it down, while this doesn’t happen in the ground up orientation.
I’m not going to say rightside up is unequivocally the “right” way, but I’m not really convinced the things you (and others) are saying is demonstrably safer in any real sense.
But bulky transformers are a thing, so there’s that. In any case, what would make the ground on top “slightly safer”?
If the plug is loose and you grab and yank it, there’s no risk of touching the hot, and the ground won’t hurt you. Also, with ground side down, loose outlets expose the hot connection when gravity pulls it down, while this doesn’t happen in the ground up orientation.
I’m not going to say rightside up is unequivocally the “right” way, but I’m not really convinced the things you (and others) are saying is demonstrably safer in any real sense.
If something conductive falls onto the contacts, it’s not bridging anything.
Technology Connections did an episode about why some plugs have holes in the flats. I believe he briefly covered this topic in that video.