I'm the OP here who couldn't print the BP at home, and then spent 35+ minutes on the phone with Delta trying to find out why. The answers I got from the multiple Delta employees I spoke with all ranged around "special security procedures" and "We are following TSA rules."

So we got the airport 2 hours early expecting SSSS and major headaches. Checked in at the Delta counter, and the TA told me "Passenger X must show photo ID to check in as part of Delta's new policys to increase security." (note: no mention of TSA here). I then informed them that Passenger X is 6 years old and his only photo ID is currently in the hands of the government at the passport renewal office somewhere.

Then the TA was totally stumped and had to make about 5 phone calls to find out how to remove the check ID code so he could print our BP - good thing we were there early, as this took about 15 minutes. Of course, it then took them another 10 minutes to find the right sort of baggage tag for his car seat.

And this increases our national security how?