Yes they do. Other certification requires the manufacture to pay fees for the use of trademarked logos and also for auditing/monitoring compliance (e.g. to verify that a product is organic is one good example or the National Heart Foundation ‘tick’ logo is another).
For a major food manufacturer with a high volume product like Vegemite, the certification costs are minor (could be less than a fraction of a cent per item - using Vegemite as an example, assuming that 22 million jars sold annually and certification costs of $1500, this would be about 0.0068 cents per Vegemite product) and would not change the cost of the food consumer's pay. The costs of the certification are also a business cost and can be deducted from the income it generates.
Any certification provides a potential marketing edge to a manufacturer and can increase exports to those countries where such certification is required. Increasing exports is not only good for the Australian economy, but also provides jobs to Australians through higher demand for Australian food product manufacturing. It also assists in supporting our rural and food manufacturing industries.
@BrendanMays, thanks for posting facts on the matter. These indisputable facts differ from many of the internet based conspiracies which are easy to find using Google and usually are from individuals or organisations with other agendas.