Hardly. Google could simply ask the children to fax in signed permission statements from their parents, as websites that actually make an effort to support child users do. Neopets had this figured out 15 years ago. Google chooses not to do that despite having the resources, and they are responsible for the consequences of that decision.
Most people aren't worried about being secure from the CIA, we're worried about being secure from random criminals at the airport or the cafe. If the CIA wants you, they can just kidnap you and lock you away anyway.
It is not advantageous for Google's executives to collaborate in the tracking of US citizens; it adds a lot more work and it makes for absolutely awful PR. I'd also like to think that they possess some moral compass (even if it's a bit slanted) which lets them understand the difference between wide scale "anonymized" tracking for the purpose of advertising and giving all that data to a bunch of humans to scrutinize and judge for the purpose of spying.
>What do you mean by anonymized tracking? Isn't building a profile on every user necessary for targeted advertising?
Yes. Anonymized wasn't the right word, perhaps "behind the curtains"? Google employees aren't actually making, looking at, or (not 100% sure of this last one) "splitting" and filtering the data to learn things about you. The process, beginning to end, is automated. This is in stark contrast to the NSA, where when they get a "hit" they will carefully and personally inspect you, your interests, and your activities.