Half the laws people are complaining about are literally this although instead of a checkbox, it asks you for the birth date of a hypothetical child whose protection you want the device to match. And they don't use a government whitelist, but expect sites to self-declare and reserve the right to take action against sites that use misleading classification.
I.e. they establish the framework for censorship and deanonymization by making everyone else responsible for child-safety, except the person that should be setting up the parental controls - all they get to do is select a "child" or "not child" option. The law doesn't require they be given any control besides that - no default whitelist of apps and websites that they could edit, no blacklist, no screen time limits, nothing. Just an easy way to hand off control to someone else. A way that would be unnecessary if they instead got real parental controls.
As explained in my other comment: https://news.ycombinator.com/item?id=49256731
I genuinely don't know if the people who keep doing this are just stupid, unreasonably contrarian, or intentionally trying to sound unreasonable (and are in favour of the UK style approach) to weaken the apparent position of being against the UK-style approach.
It's incredibly disappointing to see people constantly complain about the actually _reasonable_ implementations (that don't rely on a loss of privacy for adults _or_ children).