According to the retiring head of Australia Post running such a business is not comparable to running a Fish and Chip shop.
There is one big difference of course; if your fish and chip shop doesn't make money you get the chop, and you lose all the money you have invested in the business and, if your property is mortgaged against the business, you could lose that as well. Whilst the manager of Australia Post gets a very generous financial handshake regardless of whether the business has been run efficiently or not, and his property is not endangered.
