when I rented a car on the french side it included unlimited liability as per french law

In Aruba goes by local country ie aruba law not Netherlands and seems to be for 90000 dollar and not a million

I don't know what the st martin dutch law is and yes some rental company charge you 6 dollar day for 50,000 of coverage if there is already a million dollar policy in force that would seem not to be a worthwhile purchase

as i said never could find out what is the law on either side of st martin