We can not view prostitution as "just another job". Prostitution is rife with abuse, both in the form of human trafficking and in other forms. If prostitution should be legalized, it should not be on the grounds that it is acceptable business but rather that legalization would lead to less abuse, such as less trafficking and safer workplaces.
Criminalizing being the subject of abuse is ridiculous and nonsensical. However, criminalizing abuse certainly makes sense. This means "pimps" and "johns", rather than prostitutes. Criminalizing prostitutes only means prostitutes are afraid to seek protection out of fear of being prosecuted themselves. So if it should be illegal, then "pimps" and "johns" should be punished, not prostitutes.
There is still the argument to be made that legalizing prostitution entirely would lead to less abuse. When legal prostitution is available, people would use that rather than prostitution that's a result of trafficking, thus legalization would lead to less trafficking.
This is false. Legalizing prostitution leads to increased trafficking. (
Seo-Young Cho et al.) Legalized prostitution leads to an increased demand for prostitution overall, expanding the market, including that of trafficking.
This is far from the only study on the topic. Every time I've searched for studies on the topic my conclusions have been the same. I've yet to see any studies showing decreased trafficking with legalization. So pro-legalizers, please show me the hard evidence.