What is the percentage of “missed flights”, on international flights, due to late passengers arrival at their designated hour to the airport?
I am sure this varies by country, but I have a way to get you an estimate. It's a reasonable assumption that everyone who misses a flight just because they didn't make it to the airport in time is paged. I have heard such pages for my own flights and the flights around me.
Not every flight involves these pages. At a rough guess I would say one in 20 does. (It could be as much as one in 50 even, but let's go with 20.) International flights tend to have hundreds of passengers on them. Planes aren't always full and vary in size, let's say 200 though it could easily be more than double that.
So as a first approximation, 1 or 2 passengers in 4000 come close enough to missing their plane that they are paged for through the airport. It looks like (again from my own observations sitting at the gate people watching) about half of them actually make the flight. That means 1 or 2 in 8000 miss it. Let's call that 2 in 10,000 which is 0.02%.
More people miss flights due to bad connections (delays on the inbound plane) but those generally have little or no consequence as the airline rebooks on the next flight.