lying makes their lives easier,

Suppose my mother-in-law is a terrible knitter. But suppose she loves knitting. She loves to knit me sweaters I hate every year.

Suppose I've mentioned that it's too warm in LA for a sweater every year since I've moved here. Suppose I've also mentioned that I'm rarely out in any occasions where a sweater makes sense. Yet suppose the sweaters keep coming.

Now suppose I'm a terrible liar, and that I hate having to tell people things that are untrue. I can do one of two things:

1) Tell my mother in law that I love this year's sweater.

2) Tell my mother in law that I don't like this year's sweater.

Condition (1), for me, involves lying. I don't enjoy lying. It involves me wearing a sweater I don't like. Condition (2), for me, involves telling the truth. I enjoy telling the truth. It also frees me from this and all future sweaters.

Condition (1), for my mother in law, involves the joy of giving. It involves recognition for her labor. It validates our relationship. Condition (2), for my mother-in-law, negates the joy of giving. It invalidates her efforts. It further calls into question all the effort she has put into her knitting for me up to this point and requires her to do something else for me in the future that she will not enjoy as much.

I'm going to pick (1) every time because I'm willing to sacrifice my comfort and "moral code" in order to make my mother-in-law happy. It's all cost to me and all benefit to her, and I don't even have to think about it. "Not lying" in this instance makes my life so much easier, but I'm not going to do it.

Most people wouldn't.