In Australia, how and why are indigenous people, elderly people, and low income earners suffering food inequity?

There are a few important reasons as to why indigenous people, the elderly, and low-income earners suffer food inequity in Australia.
First, food inequity, or food insecurity, occurs when people have little to no access to nutritious foods that meet their dietary requirements and personal preferences. Those who are food insecure find that their access to nutritious food is limited by their location. For example, many indigenous groups live in isolated, rural communities; so, a lack of transport options and the high cost of obtaining nutritious foods play a factor in their food inequity/insecurity.
With low incomes, the three groups above find it a challenge to eat healthily. They must pay for transportation costs to city centers (in order to obtain the best produce), and then they must pay for the high costs of fruits and vegetables once they get there. So, many indigenous peoples, the elderly, and low-income earners depend solely on nearby stores for their sustenance. Since these convenience stores often carry the most minimal range of foods, these groups often suffer from food insecurity/inequity.
A healthy diet, of course, consists of a wide variety of produce. However, such a diet is more expensive than one which consists largely of processed carbohydrates, sugars, and oils. Unfortunately, a diet high in these three things is a major contributor to diseases such as diabetes, stroke, and heart conditions.
Additionally, indigenous people, the elderly, and low-income earners often live in crowded conditions. Several families may share a single dwelling place, and kitchen facilities may not be adequate to meet everyone's needs. A government survey found that less than forty percent of indigenous people had stoves, ovens, running water, and adequate food storage facilities.
The above are some of the main reasons that the groups you mention suffer from food inequity. For more information, please refer to the link below.