Don't get me wrong, I'm all for privacy. But between setting up the birthdate when creating my children's local account on their computers, and having to send a copy of their ID to every platform under the sun, I'd easily chose the former.
I'd even agree to a simple protocol (HTTP X-Over-18 / X-Over-21 headers?) to that.
Sure. I think clearly this thread has been talking about the OS piece specifically. I wholly disagree with having some private company that collects IDs and makes the determination themselves. If instead your browser can just ask your device if you have parental controls enabled, then that removes the privacy concern entirely, as far as I know. Is there an extra data point for browser fingerprinting? Yeah, I guess. But I would also assume that anyone who cares to avoid this fingerprinting is going to not have parental controls enabled.
Essentially, I'm confused why the world gave up so quickly on parental controls (not really confused—the alternative provides more surveillance capability).