We have had actual cases where someone mailed a bunch of anthrax through the US post.
Given that the post can be used to send dangerous physical objects, it seems prudent to maintain medium-term records of what was sent and where to assist in the prevention of this type of terrorism.
Because the alternative, is we wait till it happens, we have no record of where anything came from, and then we get to engage in a multi-month campaign of opening and inspecting mail arbitrarily considered "suspect" to try and prevent the next round.
So if somebody wanted to mail anthrax to, say, a government office, how would this stop that? Dropping off a stamped envelope in a mailbox in a different neighborhood with no witnesses is not likely to get intercepted.
And of course government efforts in "The War on Terror" would never be abused, right?
Call it what you want: if we have no records of where mail was sent from and where it got delivered too over a medium-scale timeframe, we are seriously limiting any ability to deal wit this type of activity effectively.
The term "letter bomb" is a real thing that was and still is really done.
You have to travel to the mailbox to send something from it.
That mailbox is generally surrounded by other people who might notice it's comings and goings, or unfamiliar characters posting large packages.
Frankly, the idea that metadata can't help us solve crimes but it can obviously be used to nebulously control a population is an oxymoron. Either metadata is useful, or it isn't. If it's useful, then why isn't it useful or potentially useful for dealing with crime? You can't have it both ways.
Given that the post can be used to send dangerous physical objects, it seems prudent to maintain medium-term records of what was sent and where to assist in the prevention of this type of terrorism.
Because the alternative, is we wait till it happens, we have no record of where anything came from, and then we get to engage in a multi-month campaign of opening and inspecting mail arbitrarily considered "suspect" to try and prevent the next round.