I agree, it's weird how quickly it has changed. I went to school almost exactly from 2000 to early 2010s and I saw it change before my eyes. Quite literally we were the exact school year (grade) where physical abuse became much less tolerated. I'm not sure what exactly changed, but it a stark contrast between looking at the upper years when young vs when I reached that point. The teachers verified it too, and our grades were also much higher than previous years. I remember when I was in year 3 we used to literally fight on the playground and no one cared, it was _totally_ normalised.

As you said, most 90s cartoon media portrays it pretty clearly, because it really was normal. The idea of children having physical boundaries was just not really as prominent back then, at least in my experience.