Police do not decide what rape kits are processed, prosecutors do. There are a variety of reasons kits are not processed, including the victim not cooperating,

Police do not decide what rape kits are processed, prosecutors do. There are a variety of reasons kits are not processed, including the victim not cooperating, the accused confesses or dies in prison, there turns out to not be a case (such as: victim claims Bob raped them, but Bob was at dinner with someone else and his phone/credit card records confirm it, and so on.) Prosecutors don't just go "fuck women, don't test these kits lying around!" despite what you might be led to believe by a lot of folks trying to generate outrage.