What should the age of sexual consent be, in your opinion? Name an age.
I would say age 18 is fine for full consent with anyone else 18+. For below that, 4 years or less age difference is reasonable (i.e. 19 year old with a 15 year old, 20 year old with a 16 year old should be allowed.)
16 year old with 21 year old starts to get into a situation where the 21 year old (or older) is a more mature adult and the risk is too high that they can manipulate their younger partner and take advantage of their undeveloped teenage brain.
The criminal penalties for a 21 year old with a 16 year old should be less severe than a 21 year old with a 14 year old, however.
There is no perfect solution. We need to have some standards to protect vulnerable teens and children from the influence of an older person who may be taking advantage of them.
Going back to the law, if a 16 year old prostitutes themselves out, whether out of desperation for survival or because they are under the control of an abusive pimp, they should not be arrested. Any adults (age 21 and over) should be arrested and given a reasonable jail sentence, along with any other adults involved in setting up the situation.
In fact, by not holding over the possibility of arresting them over their heads, they'll be more likely to come forward voluntarily to seek help and/or turn in those adults who took advantage of them (whether as customers or as pimps).