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.
The Sydney airport line uses the exact same rolling stock as the rest of the suburban network (and the airport stations are just stops along the line, not their own dedicated line). The surcharge is just revenue raising because the train is the easiest way to get to the airport, so fuck you, pay up.