While not related to TV (but possibly radio), My political radicalism probably peaked in 4th grade due to my surroundings. Young minds can be very easily influenced before they fully develop critical thinking.
Sure, but you still can't police the content your kids watch there passively, while conversely with Netflix or cable you can set it and forget it.
If parents are relying on "setting it and forgetting it", that's not policing at all. Youtube Kids was supposed to be a solution like this where the site would offer filtered videos for children, but it quickly resulted in the so-called Elsagate scandal where children were targeted with videos depicting things like violence, drug use, and sexual activity
It's definitely a problem for both. Lots of kids are getting radicalized too, along with the Fox News generation.