life expectancy of roof in 4 point inspection

Why in the state of Florida on a 4 point inspection a 15 year life is used on shingle roofs? When the shingle is a 25 year shingle. Who dictates this 15 year life rule to the inspectors? This is ruining my ability to obtain afordable insurance. I am not willing to re-roof my house every 10 years. Please call me 941-924-7036. Thank you. Joan