I have never liked that term. It perpetuates the notion (even if only sublimely) the Government owns and controls everything.
How can you buyback that which you have never owned?
Such a Law would be a violation of the 2nd and 4th amendments (and probably others).
Cities have events like this all over NY. Usually they turn in old rusted guns that don’t work and get 50 bucks. Then they go out and buy crack or booze.
Just crap and a good photo-op for the mayors.