"No snowflake in an avalanche ever feels responsible." -- Stainslaw Jerzy Lec
If we assume there is such thing as human free will (your quote shrinks the possibility of what we can affect with our free will), Police officers are agents who have the ability to see these environmental factors and {choose to stay officers, ignore employer-provided therapy, vote for the union leadership which negotiates their employment contract, etc.}.
We don't have as much control over our lives as we would want, but police (as individuals and as a voting bloc) have significantly more control over the lives of others than us non-police do.