A) Maybe ladies who come from abroad drop their prices because they feel they have to compete with ladies who speak good English while themselves have difficulty communicating correctly?
Anyway, that's what I did when I arrived in London for the first time 10 years ago. I spoke only French (my English was minimal) and I was charging cheaper to have customers. Now my English is far from perfect but I am able to express myself without major problems.
B) To return to the question of OP...
There is no simple answer. Price optimization depends on several factors.
I think it's extremely variable and depends on what you're offering, what "niche" you're in, how many others are in competition with you, and the general economy of the area you're in.
Exactly.
Let's say that if you charge too much, you are not competitive. But if you do not charge enough, you are perceived as worth less than the others... Personally I find that my optimal price is 150 per hour.
At the time I was charging 250 per hour, I had more time wasters, more cancellations, more discussions (more or less pleasant) on my prices, fewer regular customers.
Now I feel that my clients find that I offer a good quality / price ratio.
I think we should avoid a dogmatic position on this issue and be prepared to experiment to see what works best.