To me, there isn't any difference. I don't think companies should be REQUIRED to put those in either. However, the implementing legislation and regulation were founded on the fact the devices already existed (this special FBIOS presumably doesn't exist yet -- I was simply arguing against those who said it couldn't be done or that it was a "backdoor") and contributed substantially to overall safety. The attempts to force biometric handgun safeties tried to follow a similar pattern in requiring the devices once an effective design had been proven; IIRC at least one locality has actually passed the legislation but has not yet mandated the requirement BECAUSE no such effective design has yet been proven.