It seems you've conflated myth with lying when you call the St. Nick story a lie.
It wasn't really a conflation, it was a deliberate attempt at obfuscation :-) I doubt there are any young readers of my posts, but just in case I decided to be a little vague in the beginning.
it is lesson whereby children eventually discover that the world is not always as it seems and that one has to confront disappointment.
I'm not sure it is good at teaching the world is not as it seems, because the whole story seems a bit beyond the norm of the way the world seems since it is all quite magical in nature. And even early in life, I think we have plenty of lessons that teach us to confront disappointment, so not sure kids need any more of those. So I still think the most interesting lessons to learn, and ones we won't learn many other places, are 1) a lot of people can and will lie to you under the right set of circumstances and 2) more importantly, your desire to believe can make you believe ridiculous things.
Gone, or rare, seems to be personal humility to admit a correction in outlook and the public acceptance of being able to arrive at different conclusions and seeing that as an acceptable path of development. The world has become more fanatical.
Except for small pockets of time and in very specific places, these two issues are always problems I think. I'm not sure things are much worse than normal overall, but if you live in the western world, I'm guessing you're seeing more of this type of polarization and unwillingness to engage in productive discussion, and if so, I don't disagree about that.
I'd go so far as to say the unwillingness to admit/correct a mistake is one the major biases we suffer from and it appears to me that it is in part responsible for the increasing polarization we see in the US. I actually thought of bringing this point up in my original post, but my brain was getting a little tired after three hours and I forgot to mention it.
I feel that the longer and stronger someone promotes a particular opinion to others, the more difficult it becomes for them to admit the possibility that the opinion is wrong, because to do some makes them feel bad (and of course, they also fear it may make them look bad to other people). So bias increases as a defensive mechanism, to avoid having to admit to being wrong.