A old joke on topic:
A rich man approaches an attractive woman and says "Would you have sex with me for five million dollars?" She says "Yes". He says "Would you have sex with me for five dollars?" She says "No, what do you think I am?". He says "We've already established what you are. Now we're negotiating price".
Escorting is a side hustle for many Indys. Setting a rate above the average immediately weeds out the bargain hunters who have a firm policy of not paying more than a specific amount. A certain percentage of the clientele is only interested in Ladies who charge an above average fee, if only because they don't want to be brothers in the pink with the great unwashed.
It's really not that different from those who'll pay an extra 30 cents for a can of Campbell's soup at Loblaw's or Longo's, rather than rub shoulders with the No Frills crowd.