Someone, way back there, asked "When did quotes become inverted commas?"
Well they never did - the question is when did "inverted commas" ( which I am almost certain is a typographers phrase, back in the old, cold-lead days of printing) become "quotes?"
I don't know the date, but in my youth - last century, not the one before! - the term "inverted commas" began to be supplanted by "quotation marks," a phrase which became more and more usual and, inevitably, became shortened to "quotes."
Jo is quite right in supposing that the initial and terminal marks were different - mirror images of each other, in fact. Limited space on a typewriter put paid to that and a unified, all-purpose quotation mark was accepted. Indeed, it could well be that it was the typewritten version - patently not a "comma" of any sort, but just a short, superscripted line - gave rise to the expression. That's just a guess, based on my vast knowedge and backed by my vaster intellect, and offered in all modesty
