Here is a suggestion you might want to share with your readers. Last year I started my European vacation by renting a car from Budget at Orly Airport in Paris. The clerk asked if I wanted extra insurance (the "collision damage waiver") and I told her, "No, it is already covered by my credit card." She checked the box marked suppression de franchise and I initialed it. After I got home, I discovered that this meant I owed $350 for unnecessary insurance. Many letters to Budget have failed to get them to make an adjustment.
Now when I rent a car in a foreign country, I write "No insurance fees" in English on the form. If there is a later dispute, this will make it clear what my intention was.