Excluding my personal views, and not making an argument for or against, a question was posed as follows:

"Is there not a law against people putting the contents of their cassette into a dry type drop toilet, or any toilet with a sign forbidding it"

And the answer is NO.

Local councils can make all the "Local Laws" they like but unfortunately in most (not all) cases these are NOT legally enforceable to those who are not rate payers or residents in the municipality.

National Parks are not actually national parks, they are really federally funded state parks and as such states are entitled to create laws around their use and enforce them.

If it is a vehicular rest area on crown, state or local council land, regardless of who administers it, only the federal or state governments can impose and enforce rules. So if the local council sticks up a sign saying No this or No that, it doesn't mean Jack Sh!t legally.

For private land (including pastoral lease), the land owner can make whatever personal rules they so choose and under very specific circumstances, can evict those that don't comply, but even then you have tenants rights for the term of your lease (no paperwork is required as you are deemed to have lease contract once they take your money), so unless they got you to sign a lease agreement with a list of rules, 'before' they took your money, they can't impose conditions on the unwritten contract after the sale.

Oh, and as far as camping in vehicular rest areas or other public land, legally you can "rest" not just overnight, but as long as you "reasonably" require, in order to be "rested" and "safe" to continue your journey.
That is exactly what rest areas are for. There is no legal specification as to what rested means or the maximum period it should take in order for you to be rested so that you can safely continue on your journey.
Resting and camping are two very different things.
If a ranger or some local rent-a-cop tries to move you on, request they call the State or Federal police to do so, because you are not legally obligated to obey a direction unless you can reasonably believe that it is lawful.

Simply answer with this simple statement and do NOT embellish it in any way.

"I am tired and resting in this area. It would be unsafe for me to continue on my journey until I am rested. Because of this, I do not believe your move on directions are lawful and therefore I will not comply".

They should then capitulate, but if they then tell you to "move on in the morning" you may simply ignore that request if you are still tired in the morning and believe that it would still be unsafe for you to continue your journey.
As humans we are all different. Some of us can be rested with a quick 5 minute break. Others of us that are older may require a night, a day or even two, especially when we are ill.

Thankfully in our democracy, enforcement officials are not permitted to interpret the law in any way, that is left purely for the courts. 
The courts interpret our laws and based on court precedents the enforcement officials can enforce.
You cannot lawfully be made to undertake an "unsafe" journey which may endanger your life or the life of others, and, any informed state or federal police officer would not want you to do so.

Gday...

A long and well worded submission Hylife.

But if Local Government (councils) make a by-law it is enforceable and can attract verbal warnings, compliance and stop-work notices, on-the-spot fines and penalty infringement notices, court action and even the confiscation of property.

This reference provides information. it refers to QLD but I didn't feel it necessary to make this a longer post just to replicate the same for each state's Local Government Act -

https://www.qld.gov.au/law/laws-regulated-industries-and-accountability/queensland-laws-and-regulations/queensland-laws/about-queensland-laws/local-government-laws-across-queensland/

This paragraph is snipped from that site -

A broader advice -

Cheers - John

Ignoring local council laws and bylaws ( whether they are legally enforceable or not ) will have one final result.

The closing of local free / low cost campsites to travellers.

Hylife wrote:

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Local councils can make all the "Local Laws" they like but unfortunately in most (not all) cases these are NOT legally enforceable to those who are not rate payers or residents in the municipality.

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I am not going to get into any bun fight of what is illegal, and what is a sick bird

That is why I asked the question

My quote from my previous post
Is there not a law against people putting the contents of their cassette into a dry type drop toilet, or any toilet with a sign forbidding it
Unquote

But...

The picture below tells a story

As a side note I do not think that the sign was vandalised, it was probably the bending by the wind over a period of time

I used the post as a tripod to rest my camera on, while trying to take a photograph of the sunset over the ocean

The break in the aluminium sign was fairly clean, which indicates many small movements over a long time

If the sign had been vandalised the break would have been a bit turned up, and the paint flaking at the edges

Tongue in cheek

Perhaps there is an opening for someone to enter the local council crew
They can say that they know the secret of unbreakable signs
Then just put the sign in a frame, before putting it on the post
The piece of sign remaining was fluttering in the wind a bit