Question

why does the concept of child labor in factories seems so terrible to us today when it was a widely accepted practice in the 1800s?

Answer 1

It was a wildly accepted practice only until the Muckrakers came by.

Answer 2

Answer: Because they "needed" to work so that they grow and learn their "place"/status by how much they worked as kids. So that the boys learned to be men and the girls could learn to be house wives.