Why did Julius Caesar let the Julian calendar start in January if the Romans counted their years since the founding of Rome, which happened, according to tradition, on 21 April 753 BCE = “-1” AUC?

by Icosadodecahedron

The question is completely contained in the title. Thanks in advance!

WelfOnTheShelf

Much more can always be written about this, but while we're waiting for a fresher answer, here are some previous answers:

u/KiwiHellenist explains why the Romans didn't really use AUC, it's more of a modern convenience

And two from my own files:

Rome is celebrating its 2,774th birthday today. But why?

Why is January 1 the first day of the year?