Yes, your kids will still find that dirty magazine under the park bench that the older kids discarded. And you can't stop that unless you're willing to employ a hundred park rangers who monitor every corner of a park at every time. So no one bothers.

>Are the gore websites gonna have to ask for ID now? What about 4chan? Or is the whole point to get rid of all that stuff and just get everyone using Facebook instead? (They're the ones who pushed these laws right?)

The idea is that this closes a loophole which a bunch of websites already bypass from several other kinds of laws that punish companies for breaking age verification laws (like COPPA). The obvious defense is "well I didn't know they were 12, they clicked a button saying they were 18". So now here's a mechanism that gives them more information they have to implement.

For the range of who implements it, like always, probably goes top down. They won't cover every website under the sun, but getting the big websites will supposedly be good enough. Given how consolidated the internet is these day, maybe there is some kind of point there now.