Putting aside September 11th (which would not have been prevented by x-raying vans), there have been zero actual bombings in New York City since 1993, just one

Putting aside September 11th (which would not have been prevented by x-raying vans), there have been zero actual bombings in New York City since 1993, just one pathetic attempt. And very few other incidents. It's not a city that lives under constant fear of terrorist attack, and as such I wouldn't expect to see invasive measures like this except in response to a very specific threat.