Well the reason Sydney's bus patronage is much higher is quite simple:
buses took over the job of trams in Sydney. So really, when you add
Melbourne's bus+tram figures and put it alongside Sydney's bus figure (the
new tram is relatively insignificant as yet and the new systems have not
yet replaced buses but are running alongside) you have around the same
figure, which you can see in Daniel's piece. On street public transport
overall, Sydney and Melbourne are relatively evenly matched so there's not
much point arguing any discrepancy because there isn't any. It's the train
systems that have the big discrepancy and, as I pointed out to Daniel, the
metro should be included in the Sydney train figures because it's an
integral part of the train system. That would kick Sydney's annual train
patronage up to about 400 million, which makes the contrast with Melbourne
even more stark.

Melbourne always had a better spread of its radial network than Sydney and
it still works well because Melbourne is more centralised, but Sydney has a
rapidly growing need for cross-regional travel which the old radial network
serves poorly, so the network is being converted to a grid with the new
metro lines. This means that commuters will be attracted to using rail for
cross-regional and counter commuting services, whereas in Melbourne I think
they're more likely to drive on cross-regional routes.

Tony P