He also makes a hand-printed sign with the passenger's name and then drives to the gate of the inbound flight, parking at the bottom of the jet-bridge stairs.
Delta Air Lines was founded in the city of Macon, Georgia (originally as a crop-dusting company called Huff Daland Dusters) and later moved its headquarters about 85 miles north to Atlanta in 1941 (after running its first passenger flights under the name Delta Air Service in 1929).
Evidently Delta is not worried about it because not only is the number printed but also the record locator number for the reservation and of course the name of the passenger.