[jstoeffler]

They can do that, but it's a delicate choice: if google.com gets flagged as a "tracker domain", the google.com cookies will be deleted after 30 days of no interaction with google.com.

Probably not an issue for most of the users, but for those who don't use it very often, they'd get logged out. Not sure Google wants that.

[fake-name]

I think the original point here is that almost everyone interacts with google.com daily.

As such, if a company with a non-add business attaches a tracking business to their existing domains, they can circumvent the deletion policies.