Distilling down the responses it would seem to be a case of hyper-capitalism is the reason for the killing focus of the docs.
I unfortunately cannot watch the beaver doc on the PBS site (I will have a look for it in other places)
Dave I have an interesting cross thought about Oz culture too, in that the limited media I have experienced, Oz is usually portrayed as this desolate, intimidating place where if the incredibly dangerous animals don't kill you the weird Ozlanders will. All the scariest and strangest animals seem to come from Oz which make for very tough, but also very kind characters--see Mick Dundee and Steve Irwin
I am assuming you are talking about documentaries on Australia. Australia has a lot of desolate land, and because this land is so uncommon elsewhere it draws a lot of the focus, it has provided the incubator for so many of our unusual animals. The outback is much like a frontier as the long distances and harsh environment, even now, make it a dangerous place (even without the creatures).
I think the urban areas of Australia just do not attract the interest the dry wilderness does.
The larrikin is a long standing 'hero' of Australian culture and Dundee fits that role well. Steve Irwin was bigger overseas than here in Australia, I was in Japan when he died and heard about his death within hoursl