If it's not the super trained government appointed guardians of our safety - the clerk at the departure gate ?
Surely there should also be a TSA agent standing behind each pilot throughout the flight if they can't be sure of the pilots identity?
The 'Delta connection' flight you are on is sub-contracted out to a 2 man outfit with a single regional jet.
Pay and conditions are so poor that staff turnover is huge and the number of staff is reduced so that people barely have time to glance at the person.
It's one of the hidden costs of replacing the company security guard with the cheap outside agency.