Do you have fences, barriers or signs indicating that the relevant area it is private property? Is the car abandoned or is it a repeat offender? If it is the latter, have you asked them not to park there?
You may be able to sue the owner for trespass if it is indeed private property. A driveway to someone's land is not necessarily exclusively possessed, in that there is usually a right of way for police, public members etc. Anything beyond the driveway could be.
It is an open driveway and I have signs saying 'Do Not Park'. Why can't I have it towed? Many businesses private open car parks have signs saying 'NO PARKING - Offenders will be towed', is this unlawful?
It's often bluff.
But sometimes, rules about parking are built into the T&Cs of using the car park, often in very small print.
When this happens, the parker consents to the vehicle being clamped, towed, etc (but not impounded)
as a term of the contract.
In strata blocks, the by-laws can contain similar terms (even if these do only apply to residents).
In real life, you'd be hard pressed to fond a towie who would do it.
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.