If someone has already mentioned this, mea culpa, it's too late in the evening to review all five pages.
An observation... DL's discontinuation of curbside check-in at so many airports has to be complicating check-in, making it even harder for those unexpectedly waylaid on the way to the airport to meet the 45 minute cut-off.
A question... if someone is told that they cannot fly their scheduled itinerary due to missing the 45 minute cut-off, and they are put on standby for the next flight, is there an additional fee involved?