As it turns out it doesn’t actually cost that much on regular transit, there’s an AIRPORT SURCHARGE because it’s an “airport train”.
No wonder Americans don’t use public transit, even when the system exists it’s ridiculously difficult and expensive to use.
FYI, airport surcharges are very common. Across the bay at Oakland has an airport surcharge. Sydney has them too, which I was happy about because Melbourne doesn’t have a train (AU $25 for a bus ticket, which was sold out) nor did Hobart. I recall AREX in Incheon also having a significant fare jump for the airport stops.
For argument purposes, BART is $0.18/mile (19th Oakland <> Berryessa). That’s still pretty high for regional public transit, which is mostly due to BART’s high farebox recovery. That high recovery is now a problem with the whole pandemic and subsequent slow return of ridership.
London has a expensive express line from Heathrow to the city and a regular underground line that costs a fraction.
The Narita Express also costs significantly more than the regular train into Tokyo. Airport trains have to account for travelers with a lot of luggage and thus can carry fewer people than regular trains.