It seems that you all don't lie. Well, I lie
I don't know why other people lie but I can tell you why I do it. To escape.
For example I'll tell my bf that I go to dance tango, and in fact I go to the movies. Or I leave early in the morning saying that I'm attending my schooling, and then I jump into a random train and spend the day travelling around. I even have friends who don't exist so I can go to visit them when I want to disappear for a while. I even travel to other cities, dress up in the train toilet, meet someone outside of my usual life and pretend to be someone I am not. Things like that.
It's totally useless lies of course. It doesn't make any difference for my bf wether I go to dance or to watch a movie. And I don't do it because it's funny to fool him. I just need it. I hate the idea that someone always knows where I am. I even hate the idea that at every moment there is some person who knows where I am. I need to disappear sometimes. I need this feeling that nobody has too much information about me.
Of course as some of you said, it's because of a big underlying fear or lack of inner peace.
But I am sorry to admit, I have no problem with doing something "wrong" like this.