Why do we lie?
Unless we are talking about a psychological disorder called mythomania, we lie because of fear. We do it because, consciously or not, we think lying will help us to avoid, ease, or put off the consequences the truth might have before a situation.
Lying, however, usually worsens the consequences when time comes to face the truth. Furthermore, after lying we usually need to face the consequences of our lies too, duplicating the problem... Not to mention people will find us less and less trustworthy as our lies get caught.
Would you like an example? I'll give you two: Think about lawyers. These days all contracts must be very carefully written and very specific so that any of the parties may take advantage of any ambiguity or mistake, and keep things as agreed when negotiating. As a consequence, contracts are full of complications, redundant texts, and require a lot of analysis and distrust.
Now compare this with the world of theatre: That is a world in which, all in all, a man's word is usually enough. After all, they all know that every time someone fails "to be there every single Tuesday, Wednesday, Thursday, Friday, Saturday, and Sunday before 6 p.m.", as agreed, the play will not be able to be performed, losing all their time, money, and reputation.
Honesty might not appear to be always the best option, but it pays better revenues in the long term.
Why? + Why do we lie?