I think we've hit on a key factor, but one not recognized by the code.
That is, if an area around the pool is sufficiently inaccessible, or where it is essentially impossible for a person to sit or stand next to the pool, I can see the grid not being necessary.
For example, one of the local hotels has constructed a fake rock wall on one side of their pool, and these concrete 'rocks' - actually almost like stucco applied over styrofoam forms - form a sheer cliff face that no one is likely to ever be able to climb. Another pool I have seen has one side within 2ft. of the fence line, with the space filled with rocks and cacti. In either example, I don't see a grid being either practical or necessary.
