I really think you're over thinking this.
It's 3 minutes of sitting quietly in their desks instead of running around. 3 minutes!
Now, if your child has SN and can't handle it, then that's one thing. But if your child has no SN, then it's absolutely no big deal.
You don't know if the teacher is just going to do this once or twice to start the term off. Or if it's going to happen daily.
You don't know if it's school policy, or just this teachers.
You don't know if half the class were naughty or just one or two.
But whatever you think, you need to keep it to yourself. Life isn't fair. If my team doesn't deliver it's project we all don't get our bonus. And that's the way it should be, because it is my team. It is my responsibility to get the project delivered - whether or not it's 'my part' that was late.
And obv if the team doesn't deliver enough, the whole company can close down.
So in real life there are team punishments, and working together as a team is very important.
That is the message you should be sending to your DD.