Most people lie because of fear. People will not say what music or movies they like because they are afraid somebody else will ridicule or ostracize them for it. People will not tell their boss how miserable they are because of the fear of being fired. People will lie about the things they did because they are afraid of looking dull and boring. I thought that all lies happened due to fear. But I have realized that this is not the case. Sometimes we lie for sheer convenience.
Suppose somebody asks you how to use a comma. This is a question that has a very long answer that requires a lot of technical terms and jargon. If the person who asked you then says, "you use a comma where you take a breath, right?"
The correct answer is "no". The proper answer is, "It used to be that way, and it is still similar to that, but now there are formal rules on it." But if you said "yeah" and sent that person on their way, you definitely lied, but it was not for fear;it was 100% for your convenience.
If your characters lied for convenience, it may be difficult for readers to tell without help. A perfectly-executed lie cannot be distinguished from the truth, unless evidence is found to prove it wrong or the liar confesses. If we aren't in on it, we may not get it.
Can you make your characters lie and have it not confuse the audience, without making it plainly obvious that it is a lie?