Reasons people honk:

• It's trash day and the truck is blocking the street
• An uber has parked in the bus stop
• There's a five-block traffic jam ahead
• Friendly greeting to acquaintances*

Desired effects:

• The offending vehicle[s] move

Actual effects:

• None
• The garbage men take longer 

* This honking is effective. 

Note: maybe this page should be rewritten as a table sorted by effectiveness / outcomes.