Sure. But it would also take money/power from the police, police unions, prison guards unions, etc.
Come on, I refuse to believe that these entities are actively working to put more people in prison for no good reason.
That's bullshit, police unions represents police officers, usually union policies are made by vote.
I refuse to believe that most police officers want to lock up people for no good reason
I believe it. In New York City, we had the stop and frisk laws. Officers got caught on tape telling the cops under their command to fill a quota of arrests -- and to arrest black people. Most of the arrests were pot busts after illegal searches. (Possessing marijuana was a violation, not a crime. The cops forced people to commit a misdemeanor by emptying their pockets and displaying marijuana, which was a crime.) That was the subject of a lawsuit, which was also reported on Slashdot. It all came out in court, and Judge Schendlin wrote it up in her written decision.
The new police commissioner was complaining that cops arrest people towards the end of their shift so that they can get overtime pay. Think about that for a second. They're arresting people so that they can make more money.
As I recall, one of the strongest opponents of liberalizing drug laws in California was the prison guards' union. It was pretty clear that they wanted to keep the prisons full to protect their jobs.
That said, they may very well have insights into why weed is bad. They may have experience traffic accidents, etc.
Oh, yeah. Who has more insight into why weed is bad -- cops? Or doctors, psychiatrists and scientists?