What gives any group of people the right and/or power to make a decision on behalf of someone else?

Think of these examples and see if you have a general principle that might cover all of them.

What gives a group of people the right/power to force other people’s children to go to school?

What gives a group of people the right/power to force women to sit at the back of the bus?

What gives a group of people the right/power to forcibly prevent someone from reproducing?

If nothing gives any group these rights, then why do people so often try to force others to do things like this?

What is the difference between having the right and power to do something and having just the power to do it (but no right)?