The problem with that is that public transport to reasonably close to where you want or need to go for people in Western/NW/SW Sydney is either non-existant, over crowded or just plain not running at the times you need them to get to/from work, especially if you need to get to/from the airport. For a 24 hour city it really is a shambles. With probably close to a couple of thousand people just working at the airport at any one time the Airport link train (just the bit between central and the domestic terminals) is around $15 each way per trip (that is $30/day, not including the $40 weekly pass for the rest of the network) - which is more than my tolls ($60/4 days if I solely use the toll roads) and the fuel to travel the 40km each way to and from work each day. Though out of normal people's working hours I do avoid the toll roads where possible.
Hence the reason we see sooooooo many single driver cars all trying to either get to, or under and through, Sydney. I know other cities are just as bad though I will say I'm quite impressed getting around Melbourne for the most part and (after living on the Gold Coast for a while in the early 90's) the Brizzie freeway network is so expansive it is daunting to someone who rarely ever goes there. I thought long and hard before moving back here to Sydney after 10 years away working our way around the country. The job is well worth putting up with the commute etc though.
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