So I was at YYZ on Sunday afternoon heading back to LGA. There were about 3-4 passengers who had missed their flight earlier in the day because they were late. (assume no mis-connects from earlier flights here)

What exactly does AC do when you miss your flight?

In this case, one fellow missed his 0830 YYZ-LGA and didn't make it on standby until 1415 after I had cleared the list.
The GA mentioned all flights were over-sold until the last one of the day.

I was initially booked on the 1715 YYZ-LGA and was ahead of him on the standby list for the same 1415 flight. I guess having status (35K) trumps someone at all costs when they've missed the flight?

Are there different procedures for domestic vs trans-boarder vs international?