I think the upshot of this conversation is that each of us needs to do what makes us comfortable. If you choose to pay extra for what is likely not additional coverage, that's your choice. We are comfortable renting from AAA ( a French company, BTW), and not paying extra for liability insurance.

If you actually believe you're getting additional coverage for that additional charge, I'm not sure what to say, as it's been made very clear to me that you're not.