We can speculate from the passage that Australian cattle and sheep ranchers do not like kangaroo's because kangaroos ………

Kangaroos are found in Australia, Tasmania, New Guinea and the islands east to the Bismarcks; one species has been introduced into New Zealand. They live on land and eat grasses and other plants to survive. Their principal enemies are humans, who kill kangaroos for meat, for their hides, which are used for shoes, and because they compete for food with livestock. By the late 20th century. the number of kangaroos in Australia had increased to the point that the animals had to be systematically reduced by hunting. The animals are the best known and most distinctive representatives of the native beasts of the continent.