When you leave home everyday, you have at least three things in your possession: your keys, your purse/wallet, and your cell phone. You can't leave without your keys, either for locking the door or for starting the car. You may just suffer along without your purse or wallet, hoping you have no need for your license and getting by without any money for the day. However, you will go through hell and high water to make sure you have that cell phone. There is a high probability you have reached your destination only to discover your phone is not in its normal spot, resulting in you back tracking all the way home to retrieve your life-line.
In the past, in order to have a detailed extraction of the data a cell phone contained, you were required to send it in to a lab for dissection. This could take days in the best case, and months in the worst. Can you imagine going days, weeks or months without your cell phone? Unlike your car, a rental or loaner just is not the same. All the reminders, contacts and stored passwords are out of reach. The picture you snapped for reference can not be accessed. You can not even receive calls you were not expecting as no one has your "loaner" number.