I have found that in the USA, advertised car rental prices do not include liability insurance. When I arrive to pickup the car, I always have to pay an extra x $/day so I can legally drive. This is not related to all the optional coverages they're trying to sell. In my experience, this $x$ usually exceeds the price for the actual rental, thus I end up paying more than twice the originally advertised rate. How can I tell in advance how much this is going to be — before I arrive to the counter for picking up the car?
On the websites of Hertz or others, there is some information (without quoting prices) about supplemental liability](https://www.hertz.com/rentacar/productservice/index.jsp?targetPage=USHowProtectedAreYou.jsp#Hertz_Liability_Insurance_Supplement_%28LIS%29)), but I can't find anything on the basic insurance required to legally drive.
According to this answer, if I go to a European Hertz page, I will get a quoted price including liability insurance. Indeed, the quoted price by hertz.co.uk is more than twice the quoted price by hertz.com, which is consistent with differences I have experienced between advertised and de facto prices for car rental including the legal minimum of liability. The two screenshots below show the exact same period and location, as advertised by hertz.com (upper) and hertz.co.uk (lower):
The US one makes no mention of insurance. The UK one does, only to say that Personal insurance is not included. I guess that means personal accident insurance, not the legally minimum liability insurance. So although it appears to be not explicitly stated, the difference in price between hertz.com and hertz.co.uk is consistent with my experience of legally minimum liability insurance costing more than car rental itself. Is this indeed what explains the difference? Or is there a way to find out the costs if I rent through hertz.com, then purchase the legally minimum liability insurance as I pick up the car?
In case it matters: my license is Dutch, I live in Canada, my wife is French, lives in the US, her license is from the US. Neither of us have any other insurance. In my experience there is no difference between the price quoted for her or for me.