If I had kids, and I never will, I wouldn’t care too much about the harmless kids shows they watch on TV. I would, however, not let them on YouTube or other online video places, where the content aimed at young kids is genuinely terrifying.
There’s also just a lot of horrible shit on the internet that is totally uncensored and only a click away. The worst someone can see on TV is still compliant with the FCC so it’s safer to leave kids unsupervised in front of a TV.