Excepting travel time and security time, is the airline imposition of arriving anywhere from 45 to 1.5 hours before departure or you can't check a bag. And all

Excepting travel time and security time, is the airline imposition of arriving anywhere from 45 to 1.5 hours before departure or you can't check a bag. And all the airlines recommend arrival 1-2 hours before a flight. This is to account for myriad unknown factors that apply to airline travel that don't apply to trains.