Why can’t they make a board bag that keeps the sand out?

We were in the parking lot in Waikiki and as we were putting our parking pass in our car one girl surfer next to me said “Why can’t they make a board bag that keeps the sand out.” We turned to the three girl surfers that just returned from surfing and putting their boards in their bags and said “We solved that problem!” We told them the story of how newf surf was created and they said that “We were a genius.” I gave one of the girls as a gift my Newf Surf hat off my head and we took a photo of them.