I realized that once your airport has reached a certain size and complexity (e.g. multiple security screening areas), more and more flights are delayed because there are a few passengers that have not boarded yet (most often one passenger). Now I really like to level of realism that you have passengers in the terminal that do not use the best path or a simply not at the boarding gate in time. Unfortunately that’s very realistic .
In the real world, however, boarding will close at a certain time (sometime between 15-30 minutes before departure). I would like to see the same function in the game. It could be a setting in the “Operations Tab” where a CEO can either create a common setting (e.g. automatically close gate 5 minutes before departure, or even use a negative value like -5 minutes to allow more time for pax), or create a setting for certain stands (5 minutes before departure for small stands, 15 minutes before departure for medium stands, 30 minutes before departure for future large stands).