Dept of Local Government link here:
http://www.dlg.nsw.gov.au/dlg/dlghome/documents/information/vehicle.pdf
The document in the link refers to an onus on the landholder to protect their property from uninvited parking.
Note that parking on somebody's private land, without consent to do so,
is most commonly a tortious (civil) trespass, and only rarely (on the facts) will it amount to an offence.
Which means, for the purposes of day to day life, that the police and Council may not be all that interested.
Being (almost always) a tortious trespass, it is a dispute between the landholder and the "parker".
And you resolve it like any other civil dispute.... by negotiation of you can, and litigation if you cannot.
Which is fine in theory, but how do you get
that car off
your land
now?
And the answer is - unless the car is stolen, abandoned, or involved in an offence
(in which case it could be evidence, or even part of a crime scene),
there is not much you
can do, that does not involve committing an offence yourself.
Most of what you see written relates to parking on the common property of strata land,
or on Lot 1 (the equivalent to common property for community title land).
That accounts for the residents, but does not mean much to those who are not.