Why are wise men common in contemporary [American] nativity scenes?

It is widely supported that the wise men were not present at the time of Jesus' birth. (ie. https://christianity.stackexchange.com/questions/23369/what-is-the-basis-for-the-belief-that-the-wise-men-did-not-arrive-in-bethlehem-u) . However I only 'learned' of this quite late in my America/Protestant EFCA upbringing. I've been perplexed since as to *why the concept of wise men present during Jesus' birth appears to be propagated by Christians* during Christmas1; the symbolism is common in Chistian paraphernalia/decorations, yearly 'Away in a Manger' plays mix shepherds/wise men, and such stories are [all too often] presented as 'truth' during such time; - *Is the placement of the wise men at nativity scene common among churches that observe a 'nativity scene' Christmas*? - *When did the now 'traditional' nativity scene configuration become widespread?* Was such tied to a religious (or cultural) movement? e.g. was there a Christian book that made such popular? --- 1 I realize that celebration of Christmas is very faith/church/culture specific and most such 'traditional' practices are not biblical-based. I also understand (and respect) that many Christians do not celebrate Christmas; or do not celebrate it in this manner. I'm *not* looking for a defense, justification, or opinion of such, nor am I looking for a 'History of Christmas' except as such is immediately relevant to this *particular* perpetuated belief/story.