There was an armed robbery just a few blocks from my house at a local convienance store a few weeks ago (a fellow OCer was acctualy detained as the possible suspect while happeneing to be in the area around the time about a 1/2 mile away...supposedly he "matched the description"). He went to the store (not OCing)to find out if the armed robbery was true or if he was just being harrased for OCing, and came to find out it was robbed. He tried talking to the owner about OC, but from what he told me the owner said something along the lines of (don't quote me here word for word) "the next time anyone ocomes into my store with a gun, I'll take care of them myself".
Makes me wonder what would happen if I entered the store OCing just to spend money their with no intention to commit a crime. Would the owner/worker shoot me just because I had a gun in a holster on my hip? I don't plan on trying to find out. This makes me wonder about many other stores that have owners/workers that might do the same thing to an unsuspected OCer who has no idea that a certain store may have been robbedone too many times.
As far as the bank situation you described, if the bank decides to they could allows put a sign/sticker on the window prohibiting firearms, but all they would be doing is making a "Criminal Empowerment Zone" (though it doesn't seem to stop banks from still getting robbed).
I've never understood why people still rob banks. Most are in city limits where you have alot more witnesses, survielance cameras, the exploding ink packs that they usually put in with the money that discolors the money when they leave the premises making the money useless, and not to mention the time a criminal will do when convicted of an armed robbery. That's alot of risk to go throughto hope you make it home without being caught or having the money ruined.