TestDisk/Photorec is not just free, it is open source as well, and is available in most Linux distributions' repos. It may not be right for everyone, but it is my tool of choice.
Sure, but then the point is not about the "many people are not aware they can recover their data without paying for a commercial application".
Rest assured, and specifically I have used (besides Testdisk) both Photorec and DMDE extensively, that no tool is "perfect" and each tool may have some particular function that works where another tool doesn't, so when the game is "data recovery" the first rule is "throw (at the device) anything you can", beginning with one's tool of choice obviously, but without setting aside any other one.
