So, how long before "15 years old isn't a child" arguments start coming in?
Well, a 15 year old is objectively not a child. He or she is a teenager, a transitional stage between childhood and adulthood, not quite like either of those two stages of life. Humans are not larvae until our 18th birthdays who then metamorphose into adults. No, we develop gradually, and the society needs to accept that. The notion that anybody below 18 is a full-on child is one of the more pernicious ideas that developed over the last few decades.
As far as age of consent, I think 16 is a good compromise age, and there should be close-age exceptions. I.e. a 16 year old with a 15 year old should be allowed. Note that 16 is the age of consent in most of the developed world, including some US states, and that 18 as age of consent is the exception.
As far as being a sex worker, 18 is a good cutoff as the age of majority. Note that none of this makes forced or coerced sex ok, regardless of age, although younger ages of vicims make it worse, of course.
Note that I will most likely be attacked by the likes of Toni and Jarhyn for having a nuanced position on the matter, and because I do not think that somebody 17 years and 364 days old is a "child" who is unable to consent to sex.