The goal of the policy is supported by the voters. The polls used to measure this are shifty at best about the implementation details. Who doesn't want to prevent kids from looking at pornography? But plenty of things are popular if you ask people in a way that makes them ignore how it plays out in real life. Laws against tall buildings are a pretty good example. Land reform was extremely popular in many socialist countries until it actually happened. I'm sure you can think of other examples.

In this case the ministers know what the problems are. The policy is not new or unique to the UK and it has been done better in Louisiana of all places:

https://reason.com/2024/03/18/pornhub-pulls-out-of-seventh-s...

> The difference is in the details of complying with Louisiana's law. Verifying visitor ages in Louisiana does not require porn sites to directly collect user IDs. Rather, the state's government helped develop a third-party service called LA Wallet, which stores digital driver's licenses and serves as an online age verification credential that affords some privacy.