Apparently you just misinterpret it.
It's not meant as "40% distance loss" but "ball buried by 40%". Look at the ball down right, it proves this.
With this thinking, it will be clear that 40% sand means a different obstacle than 40% rough or 40% mulch, and that the results with different shots and clubs will vary widely. It's up to our skills to select the right solution and power.