This is an opinion by Peter Berney, National Business Development Manager, Solutions in Engineering:
“There are no differential standards for buildings on the basis of when they were constructed, or how many units they contain. However, compliance with the Building Code of Australia is not retrospective. Under the Environmental Planning and Assessment Act 1979, a building only has to comply with the Building Code of Australia at the time of construction. As a result, the Building Code of Australia does not require you to continually update your windows, balcony railings and fire doors etc.”
However, the writer goes on to explain that common sense should prevail and safety should be a priority. https://www.lookupstrata.com.au/nsw-older-building-safety-maintenance/#comments
A council may address a perceived fire safety problem in an existing building with a fire upgrading order, which is served under Section 121B Order No. 6 of the EP&A Act. Has your building received such an order?
The price of the fire door that you provided seems a bit expensive; however, does the door need to be custom made? Does the price include labour to install it? Does the frame need to be replaced? Does the sill have to be changed? Do the hinges need to be replaced to make it self closing? Does the door hardware need to be changed?
See this link to page that contains door prices …including fire doors.
https://spdoors.com.au/solid-core-and-fire-door-prices/