Whatever happened to biometric locking systems on firearms?

The tech is out there and has been for some time, so whatever happened to the fingerprint locks on firearms? Too expensive? More expensive than 1000 funerals or 1000 shattered families??? This promising technology isn't off the ground yet.... why not?? Surely it would go a long way to preventing Junior from shooting up his gym class with Dad's gun.It would surely put a serious damper on the stolen weapon market also, no??