While it seems practical to indicate whether alcohol is present in a meal or not, I haven't seen the presence of alcohol indicated on restaurant menus in Sydney.
And Sydney is a place that would be as likely as many to indicate such a thing. In Australian supermarkets, there tends to be a lot of information about foodstuffs, so you can often find out whether food contains any allergens, and whether it has any religious certifications. Some Australian restaurants get themselves certified as halal, mainly Indian restaurants, but I've also seen western-style fast food chains offering halal food (Oporto). Some restaurants also indicate whether they have allergens in their food. Also, Sydney has a higher proportion of Muslims than other parts of Australia. So if Sydney restaurants don't indicate the presence of alcohol, I'd speculate that only places with a very large or a very concentrated Muslim population (such as France, mentioned by rturnbull) would indicate such things.
As a heads up, there is some antipathy in some countries towards food labelling in general, and towards halal in particular, and people are likely to assume if you're asking about alcohol that you're a practising Muslim. While I wouldn't expect the staff to be rude to you, some fellow patrons of the restaurants might.