[gjsman-1000]

Already exists; the industry called it RTA (Restricted To Adults). Nobody used it... and it's 19 years old. Complete failure categorized under "we already tried that."

https://www.rtalabel.org

You can use it too, just put this in as a meta tag:

<meta name="RATING" content="RTA-5042-1996-1400-1577-RTA" />

Or send the following header:

Rating: RTA-5042-1996-1400-1577-RTA

[Ajedi32]

Was it legally mandated? I think that's the main idea GP is proposing. Obviously without any incentive to actually implement it there's no point.

[philipkglass]

I don't think that it matters. The big porn sites have served RTA tags for many years. Android, Windows, macOS, and iOS can all be configured to block adult content tagged with this system. That still hasn't stopped a bunch of states from passing age verification laws ostensibly targeted at protecting children from these sites.

[immibis]

Because the laws aren't about protecting children. If they were, they'd say browsers have to enforce this header and sites have to send it.

[stevenicr]

In order to accomplish that working, you'd have to legally mandate parents put the blockers on their kids devices.

Similar things exist that block based upon lists and content keywords and such.

Most parents do not want to block stuff from their kids or they would be.

If thousands of them demanded that devices came with blockers then the market would provide such devices.

Many moons ago you could argue parents did not know what the youngins would find on the internet. Today's parents definitely know, and most do nothing to restrict access.

[immibis]

It doesn't have to be mandated - parents could choose.

Even if it's mandated that kids can only use phones with a special "kid mode" turned on, even if you had to present ID to turn it on or off or buy a phone with it turned off, that would still be way less bad than what's being rammed through parliaments right now.