Part of my job is to be the guy who minds busy intersections, critically there to prevent accidents and to direct the traffic, but the more unobtrusive that one can be there then the smoother the process will flow. Ideally I should be barely noticed but people should still end up getting where they need to go, and then wonder how they got there so quickly.
Another major part of my job is to be a detective, called in when things go wrong to try to find out the cause. This is probably the most difficult part; needing the most experience, the most application, and the most rational thinking in the face of irrational pressures.
There is also a small part that needs to be the enforcer, hauling people up to face the consequences of their actions.
Of course I'm not in the police.