As far as I can tell from reading the text of the bill, this doesn't actually require anyone to realistically verify anyone's age... it just requires "account holders" (adults) at account creation time to provide a (any) birthdate for the purposes of categorizing their access by age bracket. It doesn't say anything about the information having to be accurate, and gives no penalties for such.
It applies not just to Internet sites but any software application, including operating systems. And strangely it also designates any "person that owns, maintains, or controls an application" as a "Developer".