TL;DR don't make everyone prove they're an adult (and thus who they are). Put the kids into the daycare if that's what you want the law to be.

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Don't let the kids wander Las Vegas / the adult section of town (the Internet) unsupervised?

Or even better:

Have any website that's intended for children make a Legal Claim that they are rated Child Safe / Friendly so they fall under Advertising Law coverage and/or soliciting a minor.

Then have user agents (browsers) used by children configured to limit them to those places. Or even pay for a special VPN that limits access to those places.