>>One could pass a rule requiring that
One could. But the government will not. This is not about preventing “tragedies” or keeping people safe. This government knows that the economy is just about done and the entitlement checks are going to stop soon unless it “fundamentally changes” the way we do business in America. When that happens and the overwhelming majority of people find that their new standard of living based on what some government bureaucrat/commissar decides you “need” is not very good, the people will rise up. It will just be shouting and brick throwing at first, but eventually the shooting will begin.
This government (not Obama’s government, but the government of the Two Party System as it is currently formed) needs to defang the 330 Million angry Americans before that day arrives. Universal background checks are the only means that they have at this time. They will not use your non-intrusive plan. They can’t afford to let this crisis go to waste.
I know that. My point, though, was that even if the rules were written in such a way that they would not allow the government to locate firearms but only determine the chain of custody for a firearm it physically possessed (such ability being sufficient to satisfy the claimed purpose of background checks), background checks should still be considered unacceptable unless there were also a means of ensuring that they would and could never be used to deny anyone's RKBA without due process of law.
I think my point is that arguments that background checks allow the government to build registration lists which they could use in bad faith aren't apt to sway people who perceive the government as generally acting in good faith. It's much more effective to make the point that the people pushing for background checks have openly complained that such checks presently fail to block sales to people who have not been adjudicated mentally incompetent, have never been convicted of any felony or other crime which, when committed, was punishable by loss of RKBA, and are not presently under indictment for any such crime. Some people may dismiss the notion that registration lists could facilitate confiscation as "tinfoil hat nonsense", but it's harder to dismiss the notion that Lutenberg et al. want to deny people's RKBA without due process when they have written legislation to do precisely that.