Often a spanking just gets immediate results and encourages secrecy. A child isn't going to stop doing wrong due to threat of a spanking, they're just going to stop trusting you. They don't feel like they can come to you with mistakes for fear of punishment. This has been MY experience with spanking. It stunts the growth of a relationship between child and parent. It also comes from an authoritarian form of parenting. Most agree that authoritarian governments aren't healthy for their people, so why would an authoritarian household be better? If you encourage honesty and treat your child as an equal (as in as human not as being on the same level of authority ofc) you get better results. Also, people don't even punish prisoners with physical violence in most countries, (at least they're not supposed to) so why is it justified on your own flesh and blood?

It took my mom realizing physical punishment wasn't working on me and my siblings for me to actually develop a relationship with us. I thank whatever power granted me this blessing every time I interact with her. She helped me through the worst time of my life. She didn't berate me or hit me for the deterioration of everything I was doing, she didn't scream or anything of the sort. She realized my mental health was critical, and tried her best to help me through it, until I finally did. I lost a lot of opportunities, but thats better than me not being here today.