Note the stance.
Of course, that specific pic was chosen to show ferocity. (I'm not even sure if that's a FWS, but that is a good example of why they are dangerous)
They are aggressive!! We have a deadly spider hear as well, but it prefers to hide - in fact the Indians who live with them in the woods call it "The Spider That Hides" in their native language.
We also have a very aggressive species of spider here, known to capture and kill birds, mice, etc, called a trapdoor spider. Extremely aggressive, but their poison is not even slightly dangerous to humans. Hurts like fuck to be bitten (seen it, but never been bitten - biting insects and arachnids do not seem to have any interest in biting me, stinging insects and scorpions have no such qualms, however.) and makes a mess of the local skin for a couple of weeks, but only leaves a small scar and no one is known to ever have the kind of complications from this spider bite that can cause death.
We have trapdoor spiders in Australia too.
http://www.austmus.gov.au/factsheets/trapdoor_spiders.htm
Yes, I know and they are similar to ours. South America has one of a related species, also, with the same habits, but it is the size of a dinner plate. Ours is only the size of of a small palm at their largest.
None of these have the same type of toxin that a FWS can claim, though. As I understand poisons, FWS's is more similar to a snake's poison than most spiders use. It attacks the nervous system.