We know these policies result in mass deaths; we know other policies result in many fewer deaths; we choose the former policies.

I think that is partly because enough people consider those addicted to drugs to be subhuman - enough don't care much what happens to the addicted people. IMHO in that's because we a large political movement encourages indifference to those different from us, whether the difference is race, politics, gender/sexuality, nationality, or anything else.