Lying, generally considered morally wrong, is often very useful. For example, the whole Santa argument that if your children are bad, you can tell them that Santa will not get them any presents. This is not true, but it is useful. What about situations in politics? If something catastrophic occurs and telling the people will not help the situation, should government officials needlessly worry the public? I think not.
But if you keep important information about serious situation's from people when they end up finding out, they will probably be furious because if there were possible resolutions to the situation but you lied and kept it on the low for there sake you practically just screwed everyone but it just depends on the catastrophic event am I right?. but I mean.. the whole Santa clause and the tooth fairy lies. I understand how that's not so bad because they are in fact your children and there little and it helps keep them behave and to have "an imagination" but in my opinion, I wouldn't lie to my children about that silly stuff. I believe that they deserve to know the truth. like they say.. "Its better to be fed the hurtful truth, then a beautiful lie." cause maybe if they grew older they could possibly think that lying is okay. and that shouldn't be a start for any kid. or even if you're lying to comfort someone like a friend, or keeping them from getting hurt. I believe that's morally wrong also. id prefer to be told the straight up truth then hearing something that's not true. id prefer to face the facts and get hurt then to think the situations still valid. (Whatever that situation may be).
What if we assume that no one will find out? For instance, what if hypothetically some maniac claimed that he had planted a nuclear devise in the middle of New York. I can see no way that telling the populace of the city the truth until evidence was found out; even after gaining evidence, would telling people result in anything but chaos and panic? Now, in this circumstance, they do have to do their best to evacuate the city (No small feat) and rumors will be running rampant, so obviously this is not the best scenario. Say the governing officials were able to come up with a perfectly logical, albeit untrue, reason to evacuate the city that does not create pandemonium and riots in the streets? Would this not be better?
Also, concerning the kid situation, despite your opinion, many people do tell their children these fantasy stories. Why? If lying is truly always wrong, why do so many people do it? Now, I am not implying that consensus make right. This is most certainly not true. Be this as it may, many people doing the same thing do mark a trend. I know relatively moral people who to this day insist to their children that Santa is a real entity. Are they really doing wrong?