Surely the diversions the other night alone cost the airlines $1.6m - in extra fuel, crew delays, aircraft delays/scheduling, and pax accommodation and arrangements.
Mostly likely and it cost BNE airport $0. And they still got all their landing fees when everyone eventually got there the next day.
There is also no point in comparing ILS installations in Australia with the US, as the Australian Standard is different and much more expensive. I'm sure someone who has expertise in that field could elaborate.
Whilst GLS would fantastic everywhere the reliability of it for CAT III Ops is yet to be proven. Sydney Airport's installation has been plagued with interference and various tech issues in the past.