Rattlesnakes are rarely deadly unless you get bit in a vulnerable part and can't get medical attention. About 10-15 people die a year from rattlesnakes. Bears kill about 50 people a year, cougars rarely kill anyone (something like 27 in 100 years). Gators while terrifying have only killed 26 people in over 70 years.

Cars and humans are far worse.

The thing about Australia's flora and fauna is that Australia has such a low population density. I think that if it matched the US, far more people would die from it's creepy animals etc.