Why would it be a big no-no for a teacher to touch a child but not the police, or their doctor, or their karate instructor, or their grandma?
Because none of the others (except perhaps the grandmother) take on a legal responsibility for the child as a pseudo-guardian and therefore are held to even the most absurd standard that any random parent might insist that their child must receive in terms of treatment norms. Add to that the fact that K-12 education is mandated. Parents must send their child to school (or meet homeschooling requirements). So unlike a doctor which you might choose, or karate instructor, or even a trip to grandma's, the parents are effectively being forced to hand their children over to the school for a period of time.
You're playing into irrational fears. Don't do that.
Do what? Do you know any K-12 teachers? Go ask them what the rules are in terms of touching students. And I don't mean molesting. Can't touch them on the shoulder. Can't touch them when consoling them. Certainly, can't touch them as any part of any discipline. One of the hardest things for grade school teachers to deal with is the fact that kids in those grade levels (especially about 2-5) love to run up and hug their teachers. But every one of those teachers knows that they are subject to potential lawsuit every single time it happens. What are they supposed to do? Push the child away?
And physical contact during any form of discipline is right out the window. You can do this if you are handling special ed kids (sometimes), but the school knows it's a risk. For random teachers? Bad idea. Even in situations where two kids are in a fight and a teacher attempts to pull them apart, they're setting themselves up for risk of lawsuit. I didn't respond to Smash's little diatribe because I assumed that everyone could see he's just BSing. Sometimes it's easier to just let him continue with his little delusions. But don't for a moment think that teachers are not under extreme pressure from the schools to avoid physical contact with students at all costs.
And that's exactly why we have schools calling the police. The police department is far more protected from lawsuit for engaging in actions like this than the schools. That sucks and all, but that's just the way things are.