Why do almost all the portraits on ancient Greek and Roman coins turn to the right?

Why do almost all the portraits on ancient Greek and Roman coins turn to the right?

Answer:

With my experience (from 1964) I have been convinced of the fact that the portrait engraving is much easier and more convenient if the profile of a portrait turns to the left I mean the picture on a metal mould, and right-handed toreuts-engravers.

So a master began to make an intaglio from a back side of the head and proceeding to the face didn’t cover the contour of the face with his right hand with a cutter in fingers. This position of a picture with a face line well visible let the artist control the process of engraving not breaking the face profile line to achieve the likeness with a portrait to be done. The hiding and covering with a right hand of the back f the head may cause small mistakes, but not so sufficient to destroy the similarity with a portrait needed. Resume: while making the intaglio a face line of the image and a face angle must be clear visible.

In antiquity (and now) left-handed masters were not numerous, that’s why the heads on ancient coins turned to the left are seldom met.