Would you trust Google with a scan of your passport?
Funnily enough all the actions against Google advertising business monopoly if work out would probably make privacy on the web worse in my opinion.
google is in the business of selling access to that information.
though, i can see the wisdom in painting the alternative even worse.
If they wanted to verify my identity then I would give my national identity card. I'd definitely trust them with my ID card more than most other companies