A different approach that would keep incentives properly aligned is for Facebook (et al) to publish labels in website headers asserting the age (and other) suitability of content on various sections of the site. It would then be up to client software (eg a browser) to refuse to display sites that are unsuitable for kids on devices that have been configured for kid use.

As there has been a market failure for decades at this point, it would be reasonable to give this a legislative nudge - spelling out the specific labels, requiring large websites to publish the appropriate labels, and requiring large device manufacturers to include parental controls functionality. The labels would be defined such that a website not declaring labels (small, foreign, configuration mistake, etc) would simply not be shown by software configured with parental controls, preserving the basic permissionless nature of the Internet we take for granted.

But as it stands, this mandate being pushed is horribly broken - both for subjecting all users to the age verification regime, and also for being highly inflexible for parents who have opinions about what their kids should be seeing that differ from corporate attorneys!