So, if you want to be a street photographer, post 9/11 - one thing you can do is take a cue from the old Rockford Files program. You will have to be part-photographer, and part-scam-artist. Remember, Jim Rockford kept a small printing press in the trunk of his car.
It was setup to print business cards. If he was going on a certain type of case he might print up a couple saying that he was from the I.R.S. Or he might print one up saying he was from the Environmental Protection Society. Whatever was necessary to get the bad guys.
At any rate, nowadays, you can buy a portable printer, carry it around in your backpack, and print up business cards as the need arises. However, you may have the printer as well as the camera and film confiscated. But it worked for Rockford in the pre-9/11 days.
[ed. Keep in mind that one of the main writers for the Rockford Files is even more successful these days, being the creator of The Sopranos]