You are asked for your ID in cases of buying a beer and driving a car because government law dictates it as a necessity. You are asked for your ID when you rent a car because it ties to Insurance, which is a regulated industry.

Government law does not require verification of each account user by law in the case of social media. There is a distinct difference there.

A police officer asks you for ID during a violation or for identification in terms of upholding the law. You aren't required to present your ID to other (non official) citizens on the street unless they are working in an official capacity or the law dictates that you must do so, otherwise your information can be easily stolen or misused because that person has no responsibility nor training in terms of how to properly handle and protect your personal information.

Imagine if you were asked for ID each time you bought a burger at McDonalds... Pretty silly right?

Now imagine what FB can potentially do with access to your information and behaviors through their app. A modern mobile phone can tell them a lot about you and your behaviors.