Golden Crowns commonly wander into garages or laundries at night, prompting some residents to ask "I lived here for 10 years and never seen a snake, where did t come from?" The easy answer is usually from their garden, where they shelter under loose rocks or wood during the day and throughout winter.
Newly born Red Bellies have bright red scales fringing their stomach and are a glossy jet black. As with most species, their colouration is at its most vibrant as hatchlings or new borns. "Red Belly" is a bit of a misnomer actually, as the ventral (belly) scales are more pinky grey to creamish, with only the scales on the lower sides being red.
One has to go west of the Dividing Range in NSW to find King Browns, also known as Mulga Snakes. They are actually in the Black Snake genus along with Red-Bellies and Spotted Black Snakes, rather than being closely related to Browns (Eastern, Western, Dugites, etc). This is significant with choice of anti venom.
You most probably saw an Eastern Brown or, if it was less than a metre, possibly an Yellow-faced Whip Snake.
I tend to take stories of snakes chasing people with a grain of salt.
Snakes often "bolt" when confronted by humans, usually initially, but sometimes after standing their ground for a bit. Sometimes they flee in the direction of the human, presumably because they consider it as the best escape route. Maybe they know that direction affords the safety of a hole, a hollow log or, in the case of Red Bellies, a water body in which to submerge. Maybe they know they can slither faster downhill and it is just unfortunate that is where the humans are standing.
I have seen plenty of fleeing snakes slither straight past someone standing stock still. Yet to see someone being chased.
The major reasons for anti-venom not being administered following hospital admission doe to snake bite is due to the bite being from a non-venomous or mildly venomous species, or being a "dry" (venom withheld) bite from a dangerously venomous species.
If a healthy person has suffered a significant envenomation, there is no reason for antivenom not to be administered following the usual procedures. It is never a case of allowing the body to "process the venom" if someone has taken a decent hit.
Carpet Snakes are principly mammal feeders, (although lizards make up a larger part of their diet as hatchlings), so they are not going to have a significant impact on the numbers of other snakes in the area.
South-east Queensland is the "hot spot" for snake diversity in Australia, with over 30 species found in the region. Snakes are generally fairly secretive. Just because you are not seeing them, doesn't mean they are not out there.