The simple fact that neither them nor the police have enough funds/manpower/skills to directly rehabilitate addicts means that they do the bare minimum dependin

The simple fact that neither them nor the police have enough funds/manpower/skills to directly rehabilitate addicts means that they do the bare minimum depending on what they see is their role. When using is a crime then police does it job by picking up addicts and incarcerating them. (Which might be seen as an extreme form of stochastic harm reduction, with overall very harmful externalities.) When it's not, then these needle exchanges do probabilistic prevention of specific deadly circumstances.