I suspect the people shown were selected for their ignorant replies, but it was not a bad showing, considering that American education has been intentionally destroyed over the last half century or so. At least some of the people interviewed still spoke a rudimentary form of English.
My eldest uncle had a sixth grade education, standard in his day. High school was called "High School" because it was considered higher education. Sixth grade was what they called "Grammar School". After graduating, being fond of the "great outdoors", he made took a job as a bounty hunter in Wyoming. A pair of wolf ears earned him a dollar. Cougar ears got $2.50. He got dinner by shooting the heads off quail when they came to drink at a pond or creek at the end of the day. With a .30 calibre rifle. Heads because if he shot them in the body there was nothing left but a ball of feathers. One day he came up a rise to encounter face-to-face, a cougar, drew his rifle from the saddle scabbard and pulled the trigger just as the horse shied, and plugged him between the ear. It took him two days to drag the saddle and all his ears to Laramie and collect his bounty.
You wouldn't think someone like that could be a whiz at mathematics, history and literature, and as a teenager I was of the opinion he was probably an ignorant country hick, but he dispelled that opinion when afternoon he came over to see my pet crow, sat down on the grass and recited all of Edgar Allen Poe's "The Raven." I was amazed. My mother told me he could read Latin, too.
He inherited and ran the family hardware store. Once I watched him doing his books with a pencil in a great ledger, scrolling down the long pages rapidly and writing the sum at the bottom of the column. I was amazed again. He explained that he was able to do it so fast because he was counting the nines, not just "adding". I never got that in school, even in college, where my Algebra instructor told me it was a kind of arithmetical method of calculation they used to teach, but he didn't know how it was done.
That education came out of a little one room schoolhouse. No computers. No radio, television or movies. I don't think they even had electric lights. It was primitive. Yet there was superb education in his day.
We have come down a long, long way.