It's not often that you will see a cow in the wild, however it is possible. These cows that are seen in the wild aren't the average dairy cow that you're used to. Wild cows are prone to aggression if provoked whereas dairy cows are more lenient when it comes to aggression. If you were to come across a wild cow, do not approach it as it is likely to attack you.
Dairy cows on the other hand are often found in temperate areas where grazing is supported by the climate. Victoria and New South Wales are two areas with many cow farms as they have the climate to support and uphold the grazing and farming of these cattle. If these animals were to live in a habitat or climate doesn't fit their survival needs they would be unable to produce milk or have meat that is nutritional enough for us to consume.