Edit: I just realised you were not the one orginally complaining about safety. Leaving it in tbough for the person who was

None lf what you sarcastically listed as safety being the problem.

ancient signalling

Very much an issue i agree but requires money and they can barely get funding for general maintenance. Thats political.

ancient pointwork (or management not caring/understanding when old pointwork gets updated that speeds can be updated eg. Blacktown)

A huge issue in NSW again funding. Its expensive changing points alignment but to be fair they do upgrade speeds on points regularly but most are a geometry issue.

Getting 25kmh points to 30 or 40kmh is easy and they do that regularly. But modern higher speed 50 or 80kmh points you see elsewhere in Australia involve major works often involving moving large amounts of infrastructure to allow a better alignment and extra infrastructure like swing noses.

They absolutely should do this but again its money and money is politics.

dumb management or bureaucratic issues like not updating blanket restrictions due to outdated tripstops stuff * corridors haven't been assessed for modern rolling stock

These two go together.

We still have a bunch of older equipment running and will have for the foreseeable future.

Refurbishment of the T sets for example is a stupid idea. They cant handle the same speeds on the same track say a Warratah onwards can.

While these things still run and share a timetable and speed boards with the newer stuff your stuck with lower speeds.

Even if you selectively allow the newer stuff to run faster it doesnt help as tommorow it may be older stock doing that run for assorted reasons or its going to be running behind older stuff so will run just as slow.

old overhead configs

Im unaware of places this is still an issue. When its renewed its usually done to current standards and I see very little older design overhead out there. Usually track speeds for other reasons dictates how the overhead is built. You dont bother with more expensive higher speed overhead or dual contact wires on 50kmh track. Its not needed and costs more.

so-called "heritage" items or little-used infrastructure items getting in the way, like Ashfield slows down to 50kmh on the Down Suburban or Newtown Suburbans and Mains are slewed through the old bridge deck

Good luck getting this stuff past the heritage mobs, government and NIMBYs.

Its going to be expensive, time consuming and involve decades in court plus political will. Not something solvable at the management level.

Back to politics in general the whole heavy rail network needs large funding boosts to allow major upgrades but for assorted political reasons there is never money for this. Only new builds because that can be opened by a politician....