You know what, maybe I'm giving your kids too much credit. I remember though, the times I actually learned my lesson was when I was sat down and my parents talked to me about why what I was doing was wrong, how it hurt others, and how it hurt them. I remember when I caught myself being a tough guy skipping school to smoke weed, and dukes sat me down, we had a legit heart to heart where she started crying and I didn't skip another day of high school for 2 and a half years.
If she'd just whooped my ass, I probably would have just be okay. These are young adults, it's more than just them being "bad." You give small children a couple taps and explain why what they're doing is wrong, because they cannot really understand much else, but you still talk to them.
I don't know about y'all, but if either of my parents beat me like that at 14/15, I wouldn't give a fuck about anything else they had to say about what I did. I did my dirt, got caught, got my ass beat, and that's all I need to know. Anything else about the situation is irrelevant, I woulda been saying "fuck you," in my mind.
Also, stop using yourself and others as proof that spanking works, because it's purely anecdotal. I'm not saying it doesn't work, but I am saying I don't think it's the most effective way to parent.