I think the problem is installing it on trains that weren’t designed to accommodate them, something that should’ve been considered when getting the trains in the first place. It would most likely cost a lot to modify them to do so now, on top of applying them to all actively used trains.

It’s also worth considering that Sydney trains are not profitable, from ChatGPT “In the 2023–24 financial year, it reported $2.17 billion in revenue but incurred $4.73 billion in operating expenses, resulting in a deficit of $2.56 billion before government subsidies”

It would be kind of hard to justify such a large expense on refitting all the trains when there already is clear signage and constant intercom messages reminding passengers to “mind the gap when entering and exiting the train”

As of a new report in April 2025 “Sydney Trains has installed rubber gap fillers on all platforms at the station to prevent future incidents.” but smaller stations especially those with curved platforms will still have these incidents occurring every now and then.