In my experience, in Australia and New Zealand, passengers--at least, lone men--are expected to ride in the front seat of a taxi next to the driver. It's an indication of egalitarianism--the driver will think you're stuck up if you sit in back.
Do you know of anywhere else in the world where this is expected? It's certainly not expected in the United States, where I live. And does anybody know, when a lone man is expected to sit in the front, is that the expectation for lone women too? Or for two people traveling together--are they expected to sit separately so that one is in front with the driver, or can they sit together in back?