I'm not sure where you read that, but it definitely isn't the case; many well-known courtesans from history (for example, the Greek hetaerae) had as many customers as any modern escort. A courtesan is defined by quality, not quantity.
Originally Posted by AngelOK
Well, as you are the expert on the topic, I'll have to concede that point. :-)
One thing I definitely believe is that a person has an absolute right to self-definition. An attempt to define someone from the outside is fraught with peril.