My mom is of the same mind as Ava's and Skylar's. While not her first choice, she understands that I'm doing work that suits me, makes me happy and fills a need in the world. Her concern is for my safety alone - and that as much because of the travel I do as with the work I chose.
I grew up knowing that she was for legalization, didn't see anything really wrong with the profession and had a good understanding of the motivations behind more societally sanctioned forms of transactional sex but didn't think escorting was a path worthy of much respect. She's changed her mind on that last part; I'm fortunate in that regard.
I think that questions like these appeal to a few instinctive and conditioned desires: having successful and respected children, keeping them safe, and guarding daughters' sexuality. As understandable as these urges are I was raised with the core value of making my own choices and know that if I had children I would raise them the same way.
As long as they were making choices for the right reasons and practicing the profession ethically and with a good head on their shoulders, I wouldn't worry (too much).