Checking ID is a valid security measure only when access requires certain background vetting, and the person doing the checking has direct access to the list of individuals for which access is permitted. E.g. crossing the border with a passport verifies that access is permitted through the use of Visas or database checks.... it is, therefore, a form of security to the border. Likewise, ID checking is a legitimate form of access control to restricted facilities where the checker has a means to verify that the individual is permitted access.

For a public facility, such as an airport, the ID check means absolutely nothing in terms of security.