I'm currently in Australia and have spent the last few months here, and without being biased I am afraid to say that Aussie Freeview is, well, woeful*.
The reason there are so many 'half' channels on UK Freeview is purely because 1. There are more channels overall and so less space for them all and 2. unlike in Australia, where its basically split between the 5 networks, various different broadcasting entities own Freeview multiplex slots with different contracts and carrier fees and so unless all the multiplex owners co-operate, it would be hard to consolidate them all.
In terms of the choice, Aussie Freeview is pretty bad. You only get an extra channel from each network (or 3 extra from the ABC including the new HD news service) and 1 HD service from each (which, with the exception of Ten and ABC once their news channel launches, is basically a simulcast of the main channel).
When you think that the BBC, ITV, Channel 4, Five, Sky and VMTV each have at least two (or as many as 6/7 in the BBC's case) 24hour slots, with the addition of extra channels from Discovery, QVC and Viacom, you can see why there just isn't space in the spectrum for the extra ones (like CNN) all to run 24/7. In Australia, because there are only 17 television channels (not sure where you got 22 from, unless you included the radio stations) its easier for them all to have 24hour slots.
In its defence, I do believe the Aussie Freeview should be given the allowance to add extra channels from outside the 5 networks and the 1 Community TV slot.
*with the exception of One HD. An HD free-to-air sports channel is just what Freeview UK is missing.
I agree with you about choice, I would like to see more channels besides ABC, Seven, Nine, Ten and SBS and is something that Freeview is lacking. Although One HD does stand out for me too, it does a pretty good job considering it only has one channel to broadcast all their rights on - yet, there's a good mix of sports from Australia and around he world.
I got my 22 channel count as follows, considering I live in Victoria & the list differs slightly in each state:
ABC: ABC1 (Local, VIC), ABC1 (National, NSW), ABC2, ABC3, ABC News 24 (HD channel, launching next week) & 2 'dig music' Radio Stations
Seven: Seven, 7TWO, 7HD
Nine: Nine, GO!, Nine HD,
Ten: Ten, One HD, One Digital (SD simulcast of One HD, expected to be replaced with a general entertainment channel later in the year)
SBS: SBS One, SBS Two, SBS HD & 2 'SBS Radio' Stations
C31 (Community TV)