My guess is that's because boarding a plane is a little bit like being an extra for a film, it's a hurry up and wait situation. If they printed the exact time boarding starts and people showed up then (and later), no flight would ever board on time. Better for the airline to print an earlier time and have people wait longer, so they can board as quickly as possible. Every minute behind schedule costs the airline money.

AA displays the boarding time in the app instead of the departure time once the flight gets close enough (like same day)

>If they printed the exact time boarding starts and people showed up then (and later), no flight would ever board on time

I don't understand the logic. If everyone is there at the stated boarding time and the airline has correctly allocated enough time for boarding, aren't they winning?

200 people can't board at the same second. Reality is you want orderly boarding over the course of ~ 10-15mins depending on passenger makeup. Crew also need to account for passenger with additional needs, catering recharge, etc

Yes, and the actual time is probably too close to the official take off time.

But this is why Flighty probably doesn't show it, it's irrelevant.