As far as sexually transmitted diseases go, a lot of it is "tragedy of commons". As far as population less goes, everybody profits from reducing the spread of sexually transmitted disease.
This is one of those times where I shear on Theranos. Having cheaper bloodtests that only take a drop of blood for those diseases will allow our society to act very differently when it comes to sexually transmitted disease.
This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Don't be shy, everyone has holes in their knowledge, though the fewer and the smaller we can make them, the better.
Please be respectful of other people's admitting ignorance and don't mock them for it, as they're doing a noble thing.