If a company relies on self reported ages, they don't "know" it well enough to satisfy COPPA. Probably. I'm not a lawyer but I do keep up with the latest in privacy enforcement and I think this is the way things are headed.

For the record, I'm against age verification laws. But I think companies are pushing for them because of liabilities they face under other laws, not because they would actually like to have the data.

Legally, there's a difference between "knowing" and "accurate enough for loose cannon advertisers".

Yes, but they want to show children content that is not appropriate, then claim ignorance.