Well, for context, I wouldn't even think of youtube as a media service (whether it is or isn't is another topic). I think of it as a video hosting website: subsequently I engage with it looking for a trailer, a how-to video, instructions, when a real-estate agent uploads a video of a house they're showing...and yes maybe every now and then a video or meme that someone forwards me.
As a video-hosting website, i don't think it would be responsible for me to consider giving a young child open access to it until they're old enough to basically be able to have open access to the internet: because its a video-hosting website on the internet, not a media company, and certainly not one that's vetting material suitable for small children.
Subsequently, it doesn't even get past the first psychological/physical barrier of getting into the home as an idea.
Now, bear in mind, when I grew up and was under 10, I wasn't allowed to watch cartoons before school. Cable wasn't a thing in my country. Indeed my parents would have protested that cartoons and many commercial shows "rot the brain" (and these days, i'd be inclined to agree).
I didn't feel denied, I remember watching cartoons on the weekend, and while yes, I had some hotwheels and matchbox cars (never saw a cartoon of them, did they exist?) and a voltron sheet and toy set (which I do remember as a cartoon admittedly, along with astroboy, lost cities of gold, dr who, etc). But for the most part I remember my sand pit and my building blocks more. And then just as I got old enough, home computers became a thing.
We had sesame street and playschool and mr squiggle, to be sure, but these did not have any commercial content. I also remember I had david attenborough and nature documentaries and general trivia gameshows that I liked to watch with my grandmother downstairs in the granny flat. And there was a set time each night when my parents would watch the news (which i found boring). And of course we had books!
But there were a whole HEAP of shows where the main purpose of the show/story was not even vaguely ads or consumption, and its those and similar shows that I'd be allowing, or am planning to put on a server and let my child watch from there.
As for target and walmart, well, we don't have the later in my country, and I've barely been in one of those retail stores currently for several years. Our food/groceries are delivered, and when we do go to the supermarket, its to pick something up on the way home from work or as a last minute when we're out of something: alternatively, many of the other essential things are bought from the greengrocer/bakery/dairy or other specialist retailers that are scattered around my neighbourhood, again, currently without advertising distractions targetted at children.
I mean, i get the message: I went to the supermarket as a child with my parents as well, but we weren't allowed to get anything. It was 'the rules'. I distinctly remember being allowed one Cadbury Furry Friends chocolate bar every wednesday that my mother would bring home from work: they're little blocks of chocolate about 15-20g in size.
I'm not saying we're immune from advertising. But my point is there's at least two separate worlds now: like the internet with ads, I've grown up without ads on the internet, my children are going to grow up without ads on their internet, because they're just blocked before they come in the door. There's a whole world of media out there (apparently) they aren't going to see (and looking at some of it now I'm even less inclined to let them) because at best they might have to watch it at a friends, but due to the social bubble, even the degree that its going to happen is an open question.