I find this very surprising and interesting. I'm assuming you are from the United States. What area or culture are you from specifically where this happens?

In my experience, and with people of my particular culture, parents are expected to take an active role in their children's education, which means that the parents start teaching the basics of reading, writing, and mathematics typically at about age 3. The Alphabet Song is a hallmark of early childhood, and any 3-year-old should be able to recite it. At 3-4, children should be able to start identifying individual letters.

Almost every kind of toy or children's TV show targeting this age group is also educational in nature. You literally cannot escape this.

For reading, children should be able to read any basic children's book (the kind with pictures and large font) on their own by the time they reach first grade. They should be able to at least do addition by age 5-6.

And everything I'm mentioning happens at home, in the evening and weekends. Reading fairy tales together, watching Sesame Street, playing family games like Uno and simple board games that teach counting. This isn't just how things should be, it's how things are, and I've never heard anything different.

I'm very surprised by what you're saying, especially since you make it sound like it's completely normal in your culture. Very surprised.