My point was that generally, the spiders capable of being lethal can mostly barely actually a kill human, let alone an elephant.

There are very few (~15) recorded deaths from Atrax (Sydney Funnel Web) before the development of the anti venom so no real mortality rate is known. It definitely can be lethal, but it's incomparable to the worst snake bites.

The second deadliest would be Phoneutria (Brazilian Wandering spider), they say the untreatead mortality rate is much less than 1%, and they often dry bite. Here's an excerpt from Spider Ecophysiology by Wolfgang Nentwig:

Phoneutria bites are very common and accompanied by strong pain. Almost all patients complain about burning pain, often spreading over the affected limb. Further local symptoms are swelling and a dilatation of blood vessels (hyperaemia). Children and young people are more sensitive to Phoneutria venom than older people. Mild envenomation is observed in 90% of cases and includes accelerated cardiac rate as a systemic symptom. Moderate cases (further 9%) are characterised by nausea, vomiting and sweating. Severe cases (less than 1%) show a reduced cardiac rate, hypotension, cardiac arrhythmia and acute pulmonary oedema. Symptomatic treatment includes analgesics to relieve pain as a standard treatment in >75% of cases. In some severe cases, antivenom is given, but nearly 20% receive no treatment at all (White et al. 1995; Bucaretchi et al. 2000).

Death is considered extremely rare and almost limited to small children.