Trade being the Key word. This is true throughout the Ancient World of the Mediterranean and middle east.
Even in Britain and North Africa where Roman Businessmen were plying their trade long before the Legions showed up
I see a scenario where the Traders at any given time had a Lingua Franca that was the Medium through which cultural exchange took place.
It stands to reason that when a better method or whatever was extant, change ensued.
to my header....No driver was required, necessarily.