In my experience many people routinely lie to very young children, whether it's small lies to serve a purpose ("No there's no more left so let's put it away") or larger narratives like Santa or the Tooth Fairy.
I read in this question that children are ok with the Santa Claus delusion itself because they have "incomplete knowledge" and they like fun make-believe things.
However I notice even with my very young children that people are already saying things which aren't quite true to them, and they sometimes seem to frown or otherwise get confused by it, understandably.
I like the magic of Christmas and fairy tales and everything, but one thing I remember from my own experience of growing up was trying to figure out what was right and truth. As my children grow I would like to find ways to avoid deceiving them, along the lines of 'many children believe that a man called Santa travels around...' and look at it as a legend, hopefully avoiding the direct factual question where possible.
I can endeavour to not lie to them with little every day things, but it seems like it will be difficult to find a good mix of being honest with what I say to my children consistently while still involving them in fantasy and not straying too far from convention/peers/tv/etc..
Also in my brief time as a parent it seems like my kids know when things aren't what someone says they are, even little things, and so I don't want to be undermining their trust in me by doing that just to get a result like putting on their coat or going down for their nap.
I would be really interested in any advice from others.