This is partly because all of us have this weapon, and the weapon is so immediately available. We may not have a knife with which to cut someone, but the tongue is always at hand, and we can use it even with our dying breath. Also, this sin seems so innocent when compared to others. Many of us would never even think of slugging another person, but we are not offended by repeating an unverified story. Some who would faint at the sight of blood are not at all disturbed by a battered reputation.
False witness comes in many forms, as the bible shows.
There are three closely connected NT Greek words about lying. In the PBS special The Truth About Lying , Bill Moyers reported that the seven astronauts who died in the Challenger space shuttle disaster were never told of the dangers of launching in cold temperatures. To bolster NASA's public image, information about the dangers of the launch was suppressed. In spite of their serious objections, Challenger was launched and millions witnessed the disastrous consequences. Once the private debate became public, the world learned of NASA's deception and cover-up.