People used to move a lot more quickly
I was watching a clip from an old war newsreel, and I was surprised to see how quickly people moved in those days.
Then I realized that they only seemed to have been moving quickly that it was an effect of the playback speed of the film.
So, apparently, folks were not very intelligent. If they were, they could have altered the rate of capture or playback and could have had films that played at real speed.
Which, come to think of it, somebody could still do. Play them back, that is, at real speed. Very easy, in the modern studio.
Then I finally understood. People are stupid.