And that's OK.
Since Kepler, science is not about mechanism but about prediction. There is often a rather fetishistic disdain of mechanism, that gets relegated to philosophical, coffee-table curiosities. See, for example, the various mechanisms that explain Newtonian and relativistic mechanics. Have you heard about them? Probably not; nobody cares, as the theories allow to make all the predictions than you need, and you do not need anything else.
The fact that there is no mechanism to explain a phenomenon that you can predict is not a problem. It may be a shortcoming of our understanding, but not in any case "scientifically indefensible", as you claim.
Races are outwardly visible and have different crime rates.
Young males overwhelmingly commit most crime, and you can pick them visually apart from old women who commit little crime.