Have you forgotten the Patriot Act? Bush gave up most of your rights for you when he signed that treasonous piece of paper.
I don’t know but I suspect that if you read the small print you’ll find that when you purchase a ticket to ride on public transportation you are also agreeing to meekly obey the commands of their security officers.
You are required to pass through security in order to fly on an airline. That's in the contract. Even the TSA has finally admitted they have no right to detain you if you choose to decline further screening and leave the secure area of the airport. It took a couple of court cases, but that is now official policy.
If I buy a ticket on a subway line, I didn't agree to anything but to pay the fare in exchange for a ride. Have you ever seen even a sign saying that you are consenting to a search if you ride a metro transit line? And again, even if I did agree to such a contract or if notice is provided, it becomes null and void if I decline to board the transit line.
The TSA only gets away with this crap because people allow them to. Don't allow it. It will result in some inconvenience for you, but you have no obligation to submit to an unconstitutional search. They can't search you unless you are suspected to have committed a crime.
This "stop and frisk" crap goes on in NYC, and Bloomberg knows that it's unconstitutional. But, he is betting that the victims are either not educated enough to refuse, or are afraid they will be detained and prosecuted for OTHER crimes.