This sounds like a Third world village type of situation; NSW law may protect you from losing your home but if not even one more than a quarter of Owners who vote disagree (or feel intimidated by the “big men” to not vote) with giving away common property and spending probably hundreds of dollars each to concrete over grass then welcome to my world.
A few possibilities come to mind; presumably everyone concerned is aware that you are the objector so the advice given in “Hamlet” may apply viz: “Beware Of entrance to a quarrel, but being in, Bear’t that the opposed may beware of thee”.
1. Ask the secretary to send out a new/revised EGM agenda or at least a note advising that the $3K re-instatement cost will not be bourne by the OC but by whomever authorized the work and they may also bear legal costs should they wish to dispute this (I suspect someone will find a “mate” who can do it for far less cost/ request something like this on an interim order and or the mediation/ and NCAT order which I think are mandatory with the interim order (call Fair Trading for conformation on 133220 there is only a two min. wait in my experience) ; this blackmail like element in particular is a gross affront to the rule of law and should get a strong response from NCAT.
2. New/modified agenda that the common property be sold to the parkers at market rates.