No tips for horn honkers!

A solution to obnoxious taxicab horn honking in the city

New York City is full of energy. But, the downside is there's lots of noise and distractions. A major contributor is car horns, most often honked by taxi drivers. The city has posted the warnings shown above and recently, they have vowed to crack down on honks and issue more fines. But, its not working.
Most honks are completely useless. Just obnoxious and of no value. The honkee is usually stuck - that driver can do nothing about the situation, and the honker is not making things any better. Horns should be reserved for courtesy calls - reminders, caution - or for emergencies. Honking is so prevalent that many people tune them out and when, like the boy who cried wolf, it is really crucial, they would be less effective.
I suggest we initiate devices in all vehicles with three different options for honking a horn:
    1. A siren sound that would be used only for true emergencies - it would command the most respect in the surrounding reception area. It could be the sound of a person screaming - as a warning of danger.
    2. A brief, friendly toot - this would be used to alert pedestrians and other drivers of a situation that needs attention, like caution, watch out, etc. This would command courtesy and consideration. It could even be like the sound of a person doing the Ahem cough to get attention or Psst - something more human, courteous, and less intrusive.
    3. An electric shock - used when the driver is just being rude or stupid or needs to show some power and superiority. The strength of the shock would diminish as the driver gets conditioned to stop being so stupid and rude. This would replace many honks in the city.

Another solution
An effective way to address the problem is to implement a public campaign in which cab riders vow to warn a cab driver that if he honks the horn, it will affect his tip. This can be done with a verbal statement upon entering the cab:

    "Good morning, 5th Avenue at 59th Street, please.
      If you honk the horn for any non-emergency, you will forfeit any tip."

Or by handing the driver a card as shown below. The cards can be sized to fit in one's purse or wallet - business card, credit card, or dollar bill. The cards are a more effective way for the rider to get the point across without seeming as confrontational. The bright cards might have a longer shelf life and would help push the campaign along. The notices for the drivers should be easy to store and carry, convenient to access, and convey a clear persuasive message.

The plan hits the drivers exactly where it can have the most impact. It shouldn't take long before a cab driver is motivated to change his honkin habits.
Once a critical mass of people use this threat, the drivers couldn't be sure which entering fares will cooperate.
The yellow and the band of checks convey the connection to taxicabs and the font and upper case is as is used for TAXI on the vehicles.

Items to promote the campaign
Flier to post around town, and ads to run in papers:

Sticker to post on doors of taxicabs:

Items for cab riders to hand to cabdrivers
Business card size:

Credit card size:

Dollar bill size:

Please program your car key fob so that the horn doesn't honk when you lock your car. Most cars have this option - check the Owners Manual for the instructions. Its quite simple to reprogram the key fob.
Think how much nicer it will be without those needless honks. The sound of the locks clicking still provides an aural confirmation that your car is locked. The extra horn sound is unnecessary, rude, selfish, and obnoxious. Okay, it may not be quite that bad, but it will still be nicer without the honks.
Many car key fobs allow you to double click the button to sound the horn in case you need to find your car in the lot.
Better solution: car manufacturers should program the no-honk as the default on the fob. People who feel they need the honk can program the fob to do so. But, for all the people who don't think about it or don't care, the horn option would be turned off.