I found the power of "It can be done" amazing. One country does it, everyone else thinks "It can be done, we don't want to be left behind" after 20 years of this being impossible.
Several red-states in the US had already passed similar laws before the UK - see headlines where the pornographers responded by blocking visitors geolocated in those states because they figured there's no sensible way to verify age.
Iād have gone with nationwide 24/7 facial recognition surveillance of all modes of travel and transport, something the UK and China have pioneered, and is now being rolled out as fast as possible across every other superpower, the US at the forefront.