You are really ignoring the huge opportunity cost of land that is widespread personal car use in NYC - people just tend to ignore how much land that really is because they are so used to it*. Delivery trucks wouldn't be a problem if there were a lot less cars, but cars are sarcosanct in America.

[*] The story of the original Sim City comes to mind. They originally were going to show parking lots, etc, but realized all this infrastructure actually made it look stupid and empty.