In most cases, they don't want to destroy the data. Anyone wants to retrieve their important data from a failed hard drive or a damaged media. We've had successful experiences with WeRecoverData in retrieving critical data from damaged hard drives.
Even destroying data on a computer requires work. Deleting all files and then overwriting the disk with random or unimportant data is certainly an approach. As multiple overwrites occur, the data become harder and harder to recover. Destroying the physical disk is another approach. I was surprised to find that the steel used in my disk drive was so hard that it broke my drill bit before the drill bit reached the disk platter.
With components buried in the SmartPhone which makes them hard to remove and destroy discretely, scrubbing SmartPhones is a much more challenging task.
Funny thing is, all too often when we WANT the data, it can't be retrieved.