Sure it would. Outdrives have numerous nooks and crannies, trim hoses, etc. It is exceedingly difficult to get enough paint in some of these spots to stop growth. Straight shaft drives or V drives have none of that, very simple and easy to paint under the waterline metal. Even when you do brush on 2 coats and spray the inaccessible areas, the stuff just doesn't work that well.
If you are in a high fouling area forget it. If low fouling then it can be done. So it varies by location.
Plus straight shaft/vee drive running gear is not aluminum. You can use anti fouling paint that actually works. The stuff we can use for aluminum just does not work well, at all. Maybe its different in Aust. Ask around. Make sure you are asking in the exact location you keep the boat.
You will even get barnacles growing inside the water intakes. Yes, inside. Causes hard to diagnose over heating because you don't see how far up they go. Then, you will to split the drive upper and lower units, scrape that crap out of there, and paint it INSIDE too. And do that about every other year. Although this happens on raw water pick ups on inboard, to clean them out is not a project. This is.
See been there and done that.
https://www.dropbox.com/s/nbiqnmzm0zmlt ... 5.jpg?dl=0https://www.dropbox.com/s/hsu59glgt405x ... t.JPG?dl=0Second pic is with it taken apart to clean the crap out.