Home of the bin chicken. Visit our friends:
Just wanted to remind people that you can catch the 590 bus service to DFO for 50 cents. https://jp.translink.com.au/plan-your-journey/timetables/bus/T/590
And then catch the free Skygate transfer service to the Domestic or International terminal if you need to get there cheap. https://www.skygate.com.au/sites/default/files/2018-01/Brisbane-Airport-Skygate-Loop-Timetable-July2017.pdf
Of course, that shuttle runs on an even more limited timetable than Skytrain, so it's not a great option. It stops at 6, and doesn't run at all on weekends.
I find the "4 Million" number for Perth suspect. I bet the bulk of those numbers are patrons using the line between Perth and Bayswater (the old part of the line) before the branch off to the new section. I'd be delighted to be corrected on this, but "Passengers on the airport line" doesn't mean they're going to/from the airport. The Perth <-> Bayswater corridor is very popular.
Also missed in the video: If you have a smartrider, all public transport fares in Perth cap at $5. Including the airport stations. Which is a bit moot, since all fares are $0 for the summer anyway.