Not just SV. Children working in the family business is quite common, and there's an exception for it in US child labor law.

IMO it's more common among farmers and blue collar businesses than SV types.

They (as parents) are probably looking at it as other parents do when are asking for menial house work that should be good for the family and for the child's readiness for the life ahead. I would rather prefer something like "you can do this dumb thing each day or I can teach you how to program something to do it for you" approach.

Exactly

I suspect that the op is not a normal SV resident I suspect that they come from a culture where child labor is stil Dickensian.

No, I come from rural America, where my family did have family businesses...except they did not teach me any of it... They assumed sending me to college would be the best thing for me. Yet compared to running your own business, corporate American jobs are normally terrible and make no sense.

They paid for my college which I wasted by going to vocational schools. I eventually paid my own way through university for a CS degree. Then I moved back closer to home and "work from home" mostly.

Do you think 13 year olds should be treated like 5 year olds who are not suitable to do anything except having people laugh at their reactions?

13 year olds should be treated like 13 years olds: they go to school and after they leave they get to go hang out with their boy/girlfriends, do sports, ride their bikes around or play videogames with their friends.

You do realize that has only been the norm for the last 50 years right? And IMO, the last 50 years has been some of the worst.

Mozart at 13 was not hanging out with his friends partying around.

I remember my musical teacher mentioning me about Mozart being over-solicited in his childhood and that that affected his adult life. He died young, after years of health issues.

Newflash: Not all kids are like Mozart

And was that good for him?

The criticism is not of having them work, it is of having them do a specific job, apparently whether they like it or not.