Really it comes down to the fact that many people rely on all of those transportation methods to do things like work, study, visit family, etc., and can't do it another way, because of time, money, or whatever. Under those circumstances, any government hoops to jump through should not be considered voluntary and consensual.
The NYC subway system is particularly sensitive to this, as others have pointed out, because so many people use this to work every day. You can say the bus is an alternative, but what about when they make a requirement to get on the bus? (TSA has already been caught at Greyhound stations!)
...or looked at from an entirely different angle, why should there be people trying to determine if I have a gun in a bus, on the subway, or on the streets of New York? Aren't guns legal in America? The fact of the matter is that it is so impossible to lawfully carry a gun in NYC that the cops, now using these scanners, presume you can't have one. Imagine a Texas sheriff with a scanner. "Excuse me sir, I've scanned you and you have a gun on you." "Yeah, so?"
I don't disagree with your last paragraph but I'm not sure what your point is except expressing a tautology. Let's pretend that there was no way to hide a gun (Mayor Bloomberg bans clothing in the summer as a way to curb the problem of people hiding high fat snacks in their pockets)...are you saying that police should not take notice of people carrying firearms, give the very low incidence of legally opened firearms?
How else could they enforce the city's laws, besides waiting for someone to actively commit a crime with the gun before they can ask if the gun is legally owned?
That's exactly what I'm saying. The carrying of a firearm should not be considered evidence of a crime in progress in and of itself. Nowhere else in America, save for NJ, IL, and DC, is it unusual for someone walking down the streets to be in possession of a firearm. Lawful firearm owners should not be harassed to prove their lawful status at every turn. The police can ask questions when they have reasonable suspicion.
> "Nowhere else in America, save for NJ, IL, and DC, is it unusual for someone walking down the streets to be in possession of a firearm."
Right, so we've established that legal firearm ownership is vastly outnumbered by illegal firearm ownership in the above places, and that seeing a legal firearm on the street is in fact extremely rare.
So... you live in an area where there is a substantial known presence of illegal guns, that isn't balanced by a substantial ownership of legal guns. When you see a gun, how is it not at all suspicious?
I do not see your conclusion as a logical extension of constitutional principles, it seems more informed by your own stance re: gun ownership. The constitution grants the right to search upon reasonable suspicion - I'm unsure how a gun's appearance in a place where there are almost no legal ones fails that bar.
Whether or not NY should have such strict gun laws is an entirely separate debate - as it stands it seems perfectly reasonable for the presence of a gun to be suspicious.
The NYC subway system is particularly sensitive to this, as others have pointed out, because so many people use this to work every day. You can say the bus is an alternative, but what about when they make a requirement to get on the bus? (TSA has already been caught at Greyhound stations!)
...or looked at from an entirely different angle, why should there be people trying to determine if I have a gun in a bus, on the subway, or on the streets of New York? Aren't guns legal in America? The fact of the matter is that it is so impossible to lawfully carry a gun in NYC that the cops, now using these scanners, presume you can't have one. Imagine a Texas sheriff with a scanner. "Excuse me sir, I've scanned you and you have a gun on you." "Yeah, so?"