Well hackernews wont like this but the answer is because it's enforcing the status quo. Verifying age for age-related materials and services. Some internet related services had a defacto exemption from following the laws because the enforcement logistics just werent there. A physical store that sells porn has to ID whereas online you dont, for example.
In addition there are more services, such as social media, becoming age-gated.
The enforcement hurts the sensibilities of people like us on hackernews but it's common sense to a lot of people. We live in very polarizing times, but as you've noted, it has bipartisan support. The easiest explanation is the hackernews-friendly take of lack of enforcement mechanisms is the more radical one.
Personally I think it's a bit sad but inevitable. The laws are just catching up. And there will absolutely be some good coming from it, such as holding companies liable for breaking the law.
Physical stores look at your id, they don't take a copy. Same for home delivery of alcohol at least in the UK.
They may or may not. Just like online services may or may not make a copy. That is besides the point - the point is they verify age because it's already illegal to distribute porn to minors.
No, the do not make a copy and that specifically is the point I am making. The guy looking at my id while standing in my porch is doing something ephemeral.