The situation was a little different. New Orleans isn’t NYC and NJ. No 14 story apartments, no subways, no trains, no election, not this late in the season, easier for people to get helod off of a 1 or 2 story home than the 10th floor, etc. Also, the whole country watched Katrina head straight at NO for a week while Sandy twisted and turned and no one knew where/when landfall would be until the very last.
Funny, I was looking at the storm track and it was pretty obvious for at least 36 hours that the storm was going to hit the Jersey shore at a right angle. The reason it did that was that it ran directly into a cold front from the north east, a northern hurricane. Plus the flooding of NO came from the Lake, after the storm had just missed the city. It was then that the canals betrayed the city. But anyone in the city could guess what was going to happen: the surge comes in from the South augmenting the high tide, and essentially damming up the Hudson. The whole thing then spills over lower Manhattan and the Hudson is deflected west into New Jersey. The real surprise was the size of the surge. No one could calculate that.
Once you are over 50' on the approach, it doesn't matter.