There were at least three people ahead of me and three or four behind and all were saying that they did not bring 'proof of insurance' with them.
So...as each reached the counter, it led to irate people and twice as long a wait as the agent had to go thru the reasons why.
When I got to the counter, I asked why we weren't informed of this when booking the reservation? She answered that on the car rentals own site...they do. But on other booking sites (Travelocity-which I used) they aren't responsible for those.