Do most people know how to read and write? ?

I work in a school so yes, I've had my share of students who couldn't read or write. I'm not referring to kindergarteners or first graders. I'm talking about the older ones, like third grade to high school. These kids come to my school because the parents just realized they can't read or write. Why it took them so long to realize that is a mystery. As to how those kids keep getting promoted (from other schools) year after year is the bigger problem. What do we do with them? That's where our first grade teacher comes in. She earns overtime rushing these kids, one-on-one, to learn how to read after classes. I even had to bribe one (a third grade expat) with a comic book. I said I'll give it to him if he can read and understand it already. He got it two months before the school year ended.

200 years ago, less than fifteen percent of the people on this planet could read and write. Today, the figures have reversed, and statistics show that upwards of eighty-five percent of the world is literate. No, I have never known anyone that was completely illiterate, but I have known several people who were not capable of being able to read and write at the appropriate level for someone their age. In some cases that was because the person suffered from some cognitive condition and in others it was because the person was simply thick, but no - I have never known anybody that was completely incapable of reading or writing. That's very rare in the modern world. 

Aproximately 86.4 % of the world ( over 15 y/o)  are literate.
13.6 % of the world is illiterate. That means over a Billion people are illiterate and can't read and write.
https://data.worldbank.org/indicator/SE.ADT.LITR.ZS

I myself have never to my knowledge met anyone who couldn't read or write, but my mother was a very experienced "remedial" teacher. She was employed to give extra tuition to children who for whatever reason were unable to read or write at the level of the rest of their classmates.

She told me once that she didn't believe in dyslexia. She had never met a child who couldn't be taught to read and write easily unless they had some kind of actual impairment.
Just saying ...

My maternal grandfather was illiterate and proud of it!

I also once worked for a firm whose night watchman (born in this country unlike my grandfather), who was semi-literate, at best.

Whenever "Frank" would leave a note after his shift, it might take several (literate) people several hours to figure out what he meant.

Most people that I have met understood how to read and write.
I have only met one or two people that couldn't.

People who went to school knew how to read because they were read to by their parents. When they arrived at Grade 1, they were taught how to read and write better.  Some did well. Some did poorly.

There are people who had birth defects or a bad birth and their brains were not oxygenated for several minutes. In other words, they became idiots. They did not go to a normal public school because they couldn't think.  There is one young man in my apartment building with the mind of a 16 month old child. He can walk, but he has to be led. He makes sounds but doesn't form words. He recognizes his parents but shows no recognition of other people. He is probably 27 years old.  I first saw him when he was three.

i heard my father didnt finish school cause of the war, he had to work

Well, me, for a start. I can't read *or* write. Totally illiterate. It's all Greek to me. I haven't a single clue what your question was, or how to answer it. Oh well...... these things happen, I suppose.

I was drinking in a bar in Bristol some years ago, when a most attractive and convivial young woman struck up a conversation with me.   During the course of this, she confided that she could neither read nor write - but this had not stopped her from running her own lucrative business.