> most people would
You are missing the point, "most" is not all, I don't think most people/families are like this at all, we don't do this for most people. I think you would be surprised about the number of low-income children in the US who will never see a classroom if we abandoned compulsory education. It is also an effective measure to increase equality and class mobility.
14 million children in the US are food insecure. 43 million people live in poverty, 12.9% [1]
You know how many people in the US are illiterate? 21% [2]
Do you think that number will increase or decrease if we got rid of compulsory education?
[1] https://www.nokidhungry.org/who-we-are/hunger-facts
[2] https://www.thenationalliteracyinstitute.com/post/literacy-s...