I have a feeling the numbers might not be as inflated as one might think, but I don't think people are actually watching.
This thread made me think about it, but consider this: a lot of people will have their TVs on practically 24/7 for like white-noise or what-not. When I was last at a friend's place to spend the night, she had a TV on in the game room to Boomerang, but none of us were really watching it (it's like stuffed to the brim with Tom & Jerry of various series, it's a ghost town), and it was the same in the front room once it was getting late. Old people probably have it on Nickelodeon or Cartoon Network if they're not glued to the TV because they may have their grandkids over, but I bet a lot of those kids are on their phones instead of looking at the TV screen. And places that have a lot of families like pizza parlors and airports will have the TVs on various channels, and Cartoon Network and Nickelodeon are any of the two "kids' channels" that'd be on.
So the ratings might not be wrong, technically, I just sincerely doubt you'll find a kid who actually
has watched any of these shows and can tell you what they're about or if they even like them.