Originally Posted by Matt L

Because your own insurance company may offer you more to total the car than the other guy's company. The other company doesn't want you as a repeat customer and doesn't care if they low-ball you.

My gf was tagged a few years ago by some kid in a Honda. The Honda was destroyed, but the SD was drivable but totaled. The kid's insurance company offered $1000 for the car, and would not budge from that figure. My gf's insurance company paid more than $3k for the car. She got her deductible back as well, presumably after her company sued the other.

If she had not had comprehensive insurance, she would have had to either accept the $1000 or go to court.