The technology from ten years ago was primitive by comparison to today's verification. While you can't back out original data from an altered JPG image, the intent of verification is not to do that -- it is just to verify authenticity. I have my camera set up to leave image verification turned on for all of my images. It does not prevent me from doing post processing, but it does verify whether the image has been edited.
BTW, when shooting RAW, we are actually not far from having the pure unalterable original content of the image. The contents of a RAW file is never modified during editing. The actual editing is saved in another file which may either be embedded or attached to the RAW file and it is simply a list of the editing changes to be incorporated once a copy of the RAW file is saved as a human viewable image such as JPG. Trying to edit a RAW file directly would be a very complex process.
I think that there is a lot of misconception about Photoshop editing. For example, my typical workflow consists of tonal adjustments, exposure adjustment, white balance, capture sharpening, noise reduction, correction of chromatic aberration, correction of lens distortion, cropping, resizing, color profile conversion, converting from 16 to 8 bits per pixel, and finally output sharpening. I think that it is a common misconception that Photoshop is typically used to alter the contents of an image by either adding or removing content. While it is possible to do that, there are few people who can do it well enough that it is not obvious to a trained eye. I can spot an image where the content has been manipulated almost immediately. There are many tell-tale signs that will quickly give away an altered image.
When it comes to determining the extent of processing images of wood or woodturnings, it is somewhat subjective on where to draw the line between acceptable and excessive processing. And there is no single "right" way, even within a camera saving images as JPG's, there is usually a choice of a number of shooting "styles", each with a different characteristic. Even in manually processing RAW images, nobody reaches the exact same conclusion about the final result, but I try to achieve what I remember seeing in my mind's eye.
Probably the biggest reason that the end result is somewhat nebulous in digital imaging is that there is a vast difference between what our eye/brain sees and what a digital camera sensor sees. The camera's sensor responds to light in a linear fashion and can only see light intensity -- not color. But, the sensor uses a Bayer array of red, green, and blue filters over different sensor sites and then by combining them, is able to create the illusion of color. Our eyes, on the other hand see light intensity in approximately a logarithmic fashion and determines color only in a very tiny area of the eye known as the fovea. As our eye scans around, our brain "remembers" colors and uses that to create what we call color vision. Also, we do not get the color information in a direct way from the eye -- our eyes sense the difference between colors (called opponency, we see the difference between red and green and the difference between blue and yellow). If we were able somehow to directly view the contents of a RAW image, it would appear something like a dark murky, low contrast, brownish image.
