It's different. You show an ID card to a human if you don't look old enough. They look at it and return it. The ID card doesn't get scanned or tied to all your future recreational drug purchases - you don't have an account or a trail that identifies you.
When uploading ID documents, your account gets tied to your real world identity. That's not a precedent the government should be setting, because private entities having an excuse (the law) to require identification erodes privacy, and because in the future other services could be required to ask for an identification, too. Yes, it's the slippery slope (aka "boiling the frog") argument, but that's how laws that erode privacy evolve - step by step.
Now it's account for social media, then it's porn sites, then it's forums where you might see porn or discussions on suicide, drugs or anything deemed morally hazardous. They might require an ID just to view the site or require the site to not make it public. If (or "when", if we don't oppose such laws) enough countries mandate something like this, most sites will likely require an account for all content, regardless of where the person is located, as otherwise they'll likely have to prove that they've not only geolocated the IP of the visitor, but checked that they weren't using VPNs, Tor or similar services.
As for using zero-knowledge proofs and similar technology to make it less infringing on privacy - I very much doubt the government (any government) to implement this with 100% privacy and security.