The Port Authority doesn't collect taxes. They use fees.
I think it's quite fair for New Yorkers to pay for their own bridges.
I don't have a dog in this fight, but I seem to remember the economic estimates on a terroist attack on the GWB ranging towards 13 figures. I live right near the state line, and I can report from personal experience that I-95 does not turn to gravel or hit a road block when it crosses over into Greenwich Ct. 300,000 veichles use that bridge every day, and most of them aren't stopping in NYC.
Come to think of it, at $12 a car, it seems to me that we should been able to afford a few more bridges a long time ago.