Cobra – I’m sorry but the best approach in the circumstances you describe is the one that you’re reluctant to follow, and that’s to write a letter to each resident owner outlining what you’ve stated here (only) about insufficient information being provided with the EGM Agenda, and to then deliver that; personally is ideal but under the applicable entry doors is next best lest it be seen as junk mail in letterboxes.
If that doesn’t as you say pique interest, then as the proposed landscaping would constitute an alteration and/or an addition to the Common Property and the parking works may be (depending upon the specifics), then the Agenda Item concerned should be calling for a “Special Resolution” as opposed to an “Ordinary Resolution”.
I said to (only) mention the matter of insufficient information in your letter, because if it doesn’t stir the apathetic, then as much as I hate being half-smart, it may be prudent in the circumstances for you to let the vote proceed. Then if it goes the wrong way in your assessment and it’s improperly resolved by a simple majority instead of by way of that “Special Resolution”, by a minimum 75% being in favour as determined from the lot unit entitlements of those in attendance ÷ the Plan’s aggregate entitlement as I believe it should be, then request the Chair to rule the entire Motion out-of-order; OR…..
On the other hand you could be properly smart by letting the vote proceed, and if as I suspect it’s put as an “Ordinary Resolution” and thereby improperly determined by a simple majority vote and you’re dissatisfied and/or you can substantiate a position of “dubious circumstances” where a properly put Motion and more notice / details of the costs involved in agreement would likely have given a different outcome (vote), then you could seek Orders under S153 of the NSW Strata Schemes Management Act (1996) to invalidate the vote.