And what happens when the "law missing the crucial details" is not implementable, does not have an acceptable "statutory instrument" because there exist no good solutions?

Surely there exist cases where details are unimportant - but normally what counts is achieving in the conception of a solution, because pointing at the problem is trivial. Setting an abstract goal is a no-cost effort; navigating the "compromises" is the actual work.

As I wrote, «the whole matter is absurd without full clarity on "how to do it"?»: plainly the issue is "how to have an age verification mechanism" when it clashes with the basicmost right to anonimity, and not defining the crucial detail consists in abysmal levels of inability and in criminal terror.