Replied with this to another comment, but going to say it here too so people realize it isn’t always a lack of planning:

For many people it’s out of their control. I was supposed to fly home from Japan on Thursday, with a connecting flight in Vancouver (and 4 hours between to make the transfer, plenty of time). First flight was cancelled because of a typhoon, rescheduled for the next day. Not the biggest issue, and my new itinerary still had a two hour layover in Vancouver. Then my new flight in Japan was delayed over an hour, by the time I arrived in Vancouver there were only 40 minutes before my flight home was going to leave, and only 10 minutes before boarding started. I rushed through the giant airport, customs, and security as quickly as I could. Made it just in time, but still got dirty looks from people as I boarded the plane for being late. I hope they realize one day that you can plan all the time in the world, but shit happens.