Is there a general consensus on this "air bnb" for cars model?
The prices seem absurdly cheaper than the rental shops (like 1.4k vs 4.5k), are these risky proposals?
I'd be looking at QLD, and while the Turo site appears to be very heavily US based, they do seem to have AUS prices on the web site.
How does insurance work, what happens if they cancel a car on us? are they likely to do frivolous damage claims?
The insurance is always going to be messy, should it arise. Odds are whoever owns the car hasn't insured it for putting on platforms like Turo (it costs a fortune), so it's relying on whatever Turo offers in way of insurance, which probably is questionable as they're not an insurance company. They're not a car rental company, so your credit card insurance or buying extra insurance might not work.
$3k difference seems nuts though, how long are you renting for and what kind of car? Is it a one off vehicle you found with a low rate, or is it the normal price for a similar vehicle on Turo? I'd be worried someone has an issue and is trying to get it covered by you if it's too cheap.
Beyond that, do the normal stuff, look for good feedback, take photos of the car first, make sure it's mechanically fine. Financial stress, a lot of WFH and interest rates staying high means earning extra income from a car is a big thing for some people.