However, in some countries it may seem strange if you do leave a tip. In japan, for example, the waitress might be insulted if you tipped her. In Thailand, if you left a tip, the restaurant staff probably wouldn’t be offended, but you might be pursued down the street by someone thinking you’d forgotten to take your change.
In New Zealand, although it’s unlikely anyone would chase after you, you’d definitely get some odd looks if you left a tip.