That, or a photo of your ID, or some other "proof". Depends on country too probably.
Honestly I don't think there's any relevant data google would gain from that that they don't already have unless you're very meticulous about not letting them have any, so I didn't really care.
And you can almost certainly blame "think of the children" type of legislation for that more than google trying to collect more data. Which is also what causes the country variation, it might not be needed at all in some places.
That, or a photo of your ID, or some other "proof". Depends on country too probably.
Honestly I don't think there's any relevant data google would gain from that that they don't already have unless you're very meticulous about not letting them have any, so I didn't really care.
And you can almost certainly blame "think of the children" type of legislation for that more than google trying to collect more data. Which is also what causes the country variation, it might not be needed at all in some places.