DNA test and fingerprint needles left in the street, and prosecute the criminal

The two techniques are used for very small crimes such as vehicle interference or trespassing. Sin bins and needle exchange has been provided for drug users as we understand their addiction therefore they is no excuse to put the public in danger of diseases. Children play on the street innocently because they are unaware of the risk of a needle which could change their life forever, smoking in the same car as a child is child abuse therefore how come giving a child a disease isn't abuse.