Replace “gray” with “tone”.
The most prevalent definition of “correctness” regarding exposure is the placement of the tone that would be “middle gray” at the center of the human-oriented histogram. That’s to what the spot meter in your camera is calibrated.
We all want the subject to be “just bright enough” in the images we regard, else we complain the photograph is ‘too dark’ or ‘too bright’. Where the mid-tone ends up in the rendition is of supreme importance. We lament about our crushed highlights, noisy shadows, and all that angst is really anchored on where we want the mid-tone to end up.
Musings of a demented elder gardener… 