Runaway Gun, you are quite correct about Oz DPCU's (Disruptive Pattern Combat Uniform). Some boffins spent a good deal of time noting the colours of the Australian bush and came up with a pattern and colours that are very effective.
This was back in the day when our doctrine was stopping the hordes to our north who were, apparently, dead keen on invading us. Of course, since then we've done approx zero ops on our own soil and a fair bit on other people's dirt, much like we've always done. DPCU's would probably work well anywhere where we have exported gum trees (California for one) but not so well in other places.
When we started doing extended ops in sandier areas, the boffins decided there wasn't time to do the same level of research into the DPDU as they did for the DPCU and used the nearest available sand for their reserach. That's why we are superbly equipped to conduct combat operations at Bondi, but not necessarily Baghdad. The best description I've heard of the DPDU is it makes its wearer look like a bruised bannana.