My lovely lady and I discovered an anomaly of our own. Short-hop flight, Portland, OR (PDX) to North Bend/Coos Bay, OR (OTH). We use this route to visit a small wildlife park on the Oregon coast. Takes barely an hour via a small prop-hopper (they don't need a jet on that route, and I'm not sure the runway at OTH is long enough to accommodate one in any case).
Flying this route from PDX, round-trip, is about $200 per person. Flying that same route but departing out of SeaTac (SEA) instead pretty much DOUBLES the fare to a little over $400. Essence Above, we could fly across the continent for that! If I had my pilot's license, it wouldn't even cost $200 for both of us round-trip via a single-engine Cessna!
In fact, the last time we did the trip, it was actually cheaper for us to drive 140 miles to the Portland airport to catch the flight.
AND, adding insult to injury, there is no direct flight from SEA. They simply stick you on a prop-hopper down to PDX, and have you connect to the flight going to OTH.
Go figure. And don't even get me started on the near-military security measures. Flying used to be fun -- about 15 years ago!