Put the issues of personal liberty aside, this piece by Charles C. Mann in Vanity Fair makes it clear that the U.S. is wasting money in an effort to make us feel safer when we fly:

Since 9/11, the U.S. has spent more than $1.1 trillion on homeland security.

To a large number of security analysts, this expenditure makes no sense. The vast cost is not worth the infinitesimal benefit. Not only has the actual threat from terror been exaggerated, they say, but the great bulk of the post-9/11 measures to contain it are little more than what Schneier mocks as “security theater”: actions that accomplish nothing but are designed to make the government look like it is on the job. In fact, the continuing expenditure on security may actually have made the United States less safe.

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