For all you "never had a problem with a taxi in Melbourne" people, here's what happened to me last time when I prebooked a taxi from 13CABS to the airport. Subcontinental guy shows up ~10 min late and cheerily informs me that a) this is his first day driving a cab and b) we're his first customers ever. Apparently he'd been rehearsing this phrase, because it seemed to be the only English he knew, and he had no idea how to get onto the West Gate Freeway, much less the airport. Fortunately we knew the route and managed to direct him onto it with hand signals ("Turn left! LEFT! This way!" <waves hands>) and, even to the right terminal at the airport... where it turns out that he has no idea how to operate the credit card reader. Onto the phone with a friend, jibber jabber, random button punching, nope that doesn't work, jibber jabber, more poking around, now which way does the card go in, jibber jabber, with the check-in deadline closing in we just told him to forget it, rummaged up the cash and hotfooted it. I'm not sure what annoyed me more: that we paid $70 for this, or that this fool was a licensed cabbie whose next customer was likely to be a clueless tourist.
Fortunately, my faith in Melbourne's cabs was somewhat restored the next time I needed one, which was when my wife went into labor and went from "occasional twinge" to "I think I can see the head" in the space of 15 minutes. Once our predicament was explained, the operator at West Suburban actually found a cab and told us when it would arrive (not standard practice!); indeed, it showed up in a jiffy, and the laid-back Sikh father of 3 driving it kept his cool and navigated to the hospital through the back alleys of the CBD in the worst of rush hour despite (cough) a bit of a racket from the back seat. Made it in time, Mr Turban got his tip (not that we were about to hang around waiting for change anyway...) and baby jpatokal was out less than an hour later. ^