I remember when I was a fair bit younger thoroughly enjoying trying to follow the trail at O'Reillys between Lyrebird Lookout and the Main Track.
IIRC the track that runs parallel to the Border Track is still technically a road easement, though there'd be a nuclear reaction if they ever tried to develop it . Small world isn't it; that's where I taught myself to navigate with a map and compass in the mid 1990s, prior to affordable GPS and mobiles that worked in places like that. It's also where I learned that no matter how smart you are, you can't follow the sun in rain forest, at least not if you want to end up anywhere near where you planned to. Fortunately I'd taught myself properly and made it out, very late and suitably chastened.
I've found the little 30s era track signs a few times, there are at least two sets. As you say coimon, these days there's enough tape to land a small aircraft .
Apologies for the drift down memory lane...
The days before liability became such a big issue, hey?
Government (and particularly Parks) liability was supposed to be limited by the Ipp Report reforms and resulting Civil Liability Acts in the early 2000s, but I think a lot of pollies and senior public servants still get spooked by it. Possibly for legitimate reasons; I've not kept up with the case law and maybe people are still successfully suing the government for their own ineptitude. Again, I think the new upfront signage is a step in the right direction. Unless you walk in with a bag over your head there is no possible way you can enter the YP trailhead and not see the sign. Parks have taken all reasonable steps to warn people of the risks, and IIRC that's all the new(ish) Act requires them to do.