Eyes are basically video cameras made of jello. They're amazing in the sense that, given their constraints, they work at all.

As a side note, I suspect brains are about as good at thinking as eyes are at seeing.

A substantial portion of the need for glasses is caused by kids not getting enough time outdoors. Apparently some mix of very bright light exposure and long-distance focusing is required for proper eye development. (Do a google scholar search for "myopia light exposure" for the relevant studies. https://scholar.google.com/scholar?q=myopia+outdoor+children...)

I think "need" is a strong word. I have 20/70 (maybe worse) vision, but I am fully able to do most any normal task. I am even a better shot with a gun than most of my friends, with their contacts & lasic. Yes, everything is a blur, meaning I cannot recognize faces until ~30ft, but I can recognize if it is a person, a bear, or a car. Very few things are impacted by my poor vision.

I do occasionally wear contacts, so I am aware of the advantages of having better than 20/15 vision, I just usually do not require that level of clarity.

"In China, they discovered a man born with three eyes.

LensCrafters said they could make glasses for him in about an hour and a half."

(An old Jay Leno joke. For context, LensCrafters slogan of the period was, "Quality eyeglasses... in about an hour."

Well, we need a higher visual acuity today then just a few decades ago. To tell the difference between lowercase l and uppercase I on our tiny screens if nothing else. So small errors in eye sight play a bigger role hence more ppl with glasses.