[joe_the_user]

A wide variety of government authorities occasionally walk around and talk to citizens - zone officials, fire fighters, etc. People talk to them without them carrying any threat of immediate violence (they carry the threat of later legal action sometimes but that's different).

You might be right about the cops depending on how you mean it. Now, American police may well have created some much distrust in public no one would willing speak to them, everyone would prefer some other level of authority. If you mean effective policing in general requires the constant threat of violence, I'd disagree with you there.

[slapfrog]

If people thought the reward for talking to a firefighter was a hundred dollar fine, they wouldn't be so willing to casually chat with firefighters either.

[tharne]

This is exactly why in the U.S. when there are evacuations for things like hurricanes, most towns and cities sometimes send firefighters to knock on doors and notify people. They used to send cops, but too many people simply wouldn't come to the door.