The problem with this is the person who you’ve gotten the exposure from probably didn’t know he had an STD, nor did you know you were exposed before being made aware of it. The time between being exposed to STDs and actually knowing to have it is likely to be weeks to some months. So if you were to be exposed to HIV, you wouldn’t know that until actually being made aware of it, which could take some months. That way everyone would always put down they are STD free, which would promote false idea of being in an STD free environment and possibly create a hostile environment for the infected to make former bed partners aware of their exposure.
The problem with this is the person who you’ve gotten the exposure from probably didn’t know he had an STD, nor did you know you were exposed before being made aware of it. The time between being exposed to STDs and actually knowing to have it is likely to be weeks to some months. So if you were to be exposed to HIV, you wouldn’t know that until actually being made aware of it, which could take some months. That way everyone would always put down they are STD free, which would promote false idea of being in an STD free environment and possibly create a hostile environment for the infected to make former bed partners aware of their exposure.