I don't think they are serious about privacy and even if they were I don't even want to distinguish between "children" and "adults" on the internet. Things seem to have worked fine up to this point, there doesn't appear to be a public demand for age verification, rather some murky corporations/NGOs/agencies pushing for this. I think it's pretty clear there is some other intention besides protecting children that is the goal here.
We should only need to distinguish devices with parental controls turned on from other devices, and rely on parents to set up the devices accordingly.