For no good reason. The point is that there is no year that can be put on his birth. Both Gospel accounts fail when it comes to history.
I am not a historian, I can only relay what some of them say on this topic. That was a pointless question to ask. Why did you do that? When you ask a question you should have an honest reason for asking it.
No, once again, the census was illegal in Israel since the time of David. There was an uprising due to the Census of Quirinius from conservative Jews because it broke their religious laws. Various sources that I have linked tell you that. In fact the Wiki article on it starts off with that piece of information:
"The
Census of Quirinius was a
census of the
Roman province of
Judaea taken in 6
CE, upon its formation, by the governor of
Roman Syria,
Publius Sulpicius Quirinius. The census triggered a revolt of
Jewish extremists (called
Zealots) led by
Judas of Galilee."
en.wikipedia.org
And now a question for you, since you do not seem to care that the account in Luke differs by ten years from the one in Matthew why do you even care since you have a date that neither agree upon?