When it comes to excess reduction I am happy to rely on the credit card. Terms and conditions are clearly are set out the PDS.
My ANZ platinum give me $5,000 excess reduction and my Westpac black $5,500 for any claim. (Can’t double dip of course). I don’t even have to use the card for the hire, the cover is just there.
The main requirement is that the hire car must be insured. Then the CC covers wholly or reduces the excess by the amount stated.
Collision Damage Waiver (CDW) is different from excess reduction. (Basically it is the hire company self-insuring).
If the car is uninsured then you must take up the CDW before the CC will cover the excess if any. Or you can of course do your own insurance.
I don’t think I have come across uninsured rentals In Australia, Britain or Europe.
America is different and one should always make sure that insurance/CDW is included. Or you can independently insure.