I don't get why people think it's okay to violently assault someone, solely on the basis that they are tiny and totally powerless against you. It's just weird. If someone posted here that they hit their colleague or adult family member because they were unreasonable or disobedient, they'd be eviscerated. Yet it is fine in some eyes when they're children, let alone BECAUSE they're children? I'll never forget seeing some hag at school smacking her son, yelling "NEVER" smack "HIT" smack "ANYONE" smack "SMALLER" smack "THAN" smack "YOURSELF!" and even as a kid, the irony struck me.
Hitting a kid is lazy. It's quick and it means they're scared so they do what they're told. It does not get them thinking about what they did, in fact the reverse because they'll be focused on the humiliation and hurt. It doesn't cause them to think about how to adjust their behaviour in line with what seems right - just to avoid getting into trouble when you're there to catch them at it.
It's also inherently inconsistent, because people smack when they're pissed off. How the parent is feeling at any given moment will play into that. It isn't as if reasoning with a child or talking over why what they did was wrong will change from event to event in that way. It is also not a harmless thing to do. Smacking was banned in a Nordic country (Sweden, perhaps?) and before that they, like us, had kids beaten to death by parents with semi-regularity. That started to fall after the ban, and is now very low, because social expectations shifted. If you have a culture in which most people smack their kids, you give people permission societally to be violent to them. And some people will not know where to stop, or be able to stop. You also have people reluctant to report parents who may clobber their kids abusively, because the feeling is that the level of violence may be normal rather than dangerous.
Even without that I hate it. I hate the idea that there is an acceptable level of violence an adult can use against a child. And yes, I was hit as a kid, because it was the 70s and that was normal then. It did do me harm, and my relationship with my mother harm. And she says now she wishes she'd known better, and had more constructive ways to discipline, as she likes using them with her grandchildren and she thinks that violence was actually a miserable lose/lose.
I just don't get how or why anyone can defend or justify violence towards kids as a norm.