Originally Posted by sxmpete
In France and the Netherlands, it is required that car rentals include 3rd party liability insurance.

https://www.autoeurope.ca/driving-information/france/

https://www.autoeurope.ca/driving-information/netherlands/

Since French SXM is a collectivity of France and Dutch SXM is part of the Kingdom of Netherllands, I assume they are bound by the same laws and therefor, liability is included.
This suggests that the 'optional' liability is not really required.