As a GM in a resto I have my own way of dealing with the street sellers. Simply, my place is off limits to them, and my guests are not to be bothered by them. I and my staff politely ask them to leave ONCE, and if not they are shown the door.
However, conversely, I also recognize that as aggressive of some of these folks can be they are, just like the rest of us, trying to crank out a living, and it´s not exactly drugs or other horrid substances they are selling. Factually just the other day I got a great deal on note pads from one guy!
I think the deciding factor in how they are ¨given the boot¨ under any circumstances is the level of respect they show when they come in. For example, if a seller asks me or one of my staff if they can vend their wares, while permission is denied, they are offered a beverage ¨to go¨ as a show of respect and kindness in return, nonetheless.
The challenge seems to be the local culture is that this practice is acceptable, and to some extent I understand that. When in Rome..... However, when you´re in BIG APPLE, you´re in New York!