"So do you think it is right that a child, should be allowed to work 40 hours plus a week, missing out on important education..."
They're not missing out on important education. They're GETTING an important education. They have schoolwork and tutors. And moreover, I would argue they are learning a great deal about responsibility, working together, time management, and much more than traditional schooling provides.
Just because it's not a traditional education doesn't mean it's a lack of education.
Moreover, they are making a good deal of money- money that will undoubtedly be placed in savings to provide for them in the future.
This isn't some Dickensian torture tale. It's not a sweatshop. It's Broadway. These kids have a slew of people looking out for their welfare- their parents, the producers, the production staff, their tutors, their guardians.
You have literally no statistics or facts to back anything you're saying up. It's all conjecture. Your sense of outrage is greater than your sense of reality.
"...everyone finally shut up, and the audience could enjoy the beginning of the Anatevka Pogram in peace."