Yeah, I don't think that's a good metric for "greater metro". Some of the "major" airports they listed were the closest for a grand total of about 3000 people.
I live in a small rural college town in upstate NY that has its own municipal airport; there are more than 3000 people here (especially during the school year!) for whom this is the closest airport, and it's...well, it's tiny, with (AFAIK) zero regular flights to or from anywhere else.
The closest cities are Utica and Syracuse, each about 30 miles away. Only Syracuse has an airport that's worth driving to if you don't own your own plane (SYR is on the list as being closest for 1.2 million people—probably including me? The maps aren't loading, so I can't tell), and I've never heard anyone describe Syracuse, NY as being a "greater metro area".
I'm not sure if there is a proper definition for an international airport, but I'd think of it as an airport with US Customs and/or Immigration services.
I think you'd be surprised how many there are, especially within a few hundred miles of the Canadian or Mexican border! My local general aviation airport, with no commercial passenger flights, is an international airport because of nearby business/industrial activity.
You could also just draw a line further up the list. 100K passengers/year is under 300/day so you may be looking at a handful of regional jet flights that are mostly (or only) to the nearest significant airport.
Just eyeballing the list, what I'd consider a "significant" airport probably has a cutoff closer to a million passengers per year.
I live in a small rural college town in upstate NY that has its own municipal airport; there are more than 3000 people here (especially during the school year!) for whom this is the closest airport, and it's...well, it's tiny, with (AFAIK) zero regular flights to or from anywhere else.
The closest cities are Utica and Syracuse, each about 30 miles away. Only Syracuse has an airport that's worth driving to if you don't own your own plane (SYR is on the list as being closest for 1.2 million people—probably including me? The maps aren't loading, so I can't tell), and I've never heard anyone describe Syracuse, NY as being a "greater metro area".