I asked a cop about this once after I heard about NY doing this early in the year.
Apparently the only thing the local police can do is bring you to the station, then hand you some sort of citation and let you go (citation, fine etc depends on jurisdiction) and they can't take you to the judge over it either so besides the fine its unenforcable.
They apparently just bring you to the station for optics, but in reality they could just hand you the ticket right there and let you know that theres no option for an arrest or hearing... but if they started doing that then people wouldn't follow the rules because they'd know there wouldn't be much of a risk by breaking it.
Such a stupid planet we got going on here..