Having operated into the NY area for many years, maybe I can give a little insight to some of the items that are currently being discussed on this thread. Currently, I am flying a Cessna 206 Amphibian into the East River on a regular basis. It has been my experience, that the float and helicopter guys are communicating their positions and intentions very well. And everyone works together.
First: The exclusions go up to 1100 ft MSL to give IFR traffic adequate vertical spacing. You have IFR traffic arriving, departing and being vectored into LGA, JFK, EWR and TEB.
Second: TCAS would be a total waste as most of the pilots that regularly fly into the exclusions would turn the unit off because they are getting way too many false warnings. And yes they would be getting several per flight.
Three: If you look at the terminal chart, there is a note that the helicopter routes are on the back. When you look at that chart, it only shows a small portion of the routing with a note that gives the frequencies and advises that traffic is responsible for see and avoid. The helicopter chart for that area, shows more detail and gives more information.
As for ADS-B, I think that TIS would be a quicker. viable option, for the immediate future.
The option of limiting helicopter altitudes is a problem as the operators are trying to vary the altitudes due to noise complaints.
More ATC control of the area would make the current situation much worst. Due to the buildings there is little or no radar coverage.
Based on the information so far, if the Piper did have an emergency, to me it appears that everyone was at the wrong place at the wrong time. If it was an engine failure, the helicopter pilot, IF he did see the Piper, didn't know of the airplane's situation and operated the helicopter based on the information he had.
The biggest issue is that EVERYONE that operates in these exclusions needs to understand the rules and procedures and follow them. Plus communicate clearly position and intentions.
As for the taxi driver remark, I have ridden in NYC taxis. Tightly regulated? NOT!!!