Comcare is the bucket of money that covers them when somebody litigates against them, which is fairly regular. No individual external insurance company covers them as obviously the insurance company would go broke.
Naturally it is the taxpayer who provides the money that goes into the tin.
I am not sure of the exact process but any payout CASA make that is kept under 100k escapes scrutiny or in depth explanation, anything over 100k and someone at CASA receives a pineapple, allegedly.
Good old taxpayer topping up that slush fund and filling the trough to the brim
There truly is a pot if gold at the end of the CASA rainbow! (or perhaps a pot of pony pooh).