Even more "radical" would be not giving the child a tablet at all.

There are good things on YouTube. And, their friends watch YouTube.

I do agree there are good things on YouTube, but there are also horrific, definitely not age appropriate things, and there is not enough control to keep one flowing into the other. We watch YouTube as a family, but we're fortunate in that we all like the same content. But in my opinion, supervision is the only true way to make sure they're only seeing appropriate things.

Also, "their friends are doing it" is a terrible reason to let them do it, IMHO.

If they're so young they get sucked into those weird meme videos they're probably too young for the device, if they're older than that try impressing upon the importance of viewing useful content.

And take it away if you catch them watching pointless stuff.

You can just download those and show them instead of having them browse around Youtube.

But I guess it takes time and effort to do that

I wish my parents had let the "my friends are doing it" excuse work. You're easy.