There is no reason to do this unless there is a reason of suspicion, and a parent traveling with a child is not a strong enough reason, we would be calling the police all the time.
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No it's not. As a single father the only time I had to prove I was the father was picking up my child from school, which completely makes sense because the school has responsibility for that child.
You guys want to live in a police state huh? Maybe NYC needs to bring back stop and frisk.