The thing is, if the country wants age verification, the country has to give a way to verify the age of their citizens. A website by the government that returns an encrypted cookie verifying the user as adult would be the solution. The work is on the government as they are enforcing a rule.

Another way for the government is to verify a company to do this work, with the security this entails.

I don't think politicians ever consult someone for these changes. They just want to de-anonymize the internet.