Firstly I must apologise for my fellow Australians, I have tried and tried and tried to explain to some Aussies about tipping on cruise ships but the message doesn't seem to get in. I rarely tip when I am at home but I always tip on the ship.
Your comment about the restaurant puzzles me, I am from Melbourne and the only thing I can think of is a service charge if it were a Sunday or public holiday. Our penalty wages are really high on those days and some restaurants charge a service fee to help cover the wages otherwise it would not be worth them opening the doors.
As for the original poster, tipping is not expected here in Australia but unfortunately it is creeping in especially if they hear an American accent. I am not saying it is right but I have seen in happen.
We do not tip doormen, concierge or even the person bringing ice or your bags. I usually round up a taxi fare eg $26 I would probably give $30 just for the convenience of not asking for change. If I went out for dinner, again the bill is usually rounded up for convenience.
Eg $88 we would pay 90 or 100. You will not be chased down the street or made to feel bad.
Remember our wages are reasonable here but if a tip was offered it will probably not be refused.
PS if your are embarking in an Australian port you do NOT need to tip the guys taking your bags, they will not wait around with there hand out or subtly threaten that your bags will not make it on the ship.