Back in the 1920s and 1930s, vagabond pilots called barnstormers flew all around America carrying passengers for money. There were few airports back then, so they landed mostly in farm fields. Cows were known to eat the fabric off of planes, so they were avoided whenever possible. It's part of aviation folklore*. Perhaps barnstormers didn't exist in Australia so they may not have heard those stories.

*Another cow-related piece of aviation folklore is that cows can serve as "4 legged windsocks." It's always best to take off and land into the wind, so knowing the wind direction is important. According to folklore, if you look at a bunch of cows, most of them will be standing looking downwind. Perhaps they're looking for possible predators trying to sneek up on the herd. Based on my observations, it seems this piece of folklore is true.