> pain itself is predicated on its accurate coupling to injury, since the purpose of pain is inhibitory
> pain very much does indicate tissue damage
These statements are not supported by modern research. The bio-psycho-social model indicates that pain is a threat detection and deterrent mechanism, NOT a "status report" from the painful tissue to the brain. In other words, the brain is concerned that something might lead to physical trauma, yet none need to have taken place for pain to be generated.
There are certainly biological inputs to the "pain generator" function of the brain (like sensing a foreign object touching one's skin), but psychological factors/contexts and social factors/contexts can be equally strong inputs (and ultimately generate a significant pain experience without any, or with very little, biological input).
Think of the magnitude of pain response to a given situation as an indicator sitting somewhere on a spectrum between "benign" and "dangerous". The more psychologically threatened one feels, the more the pain response will be shifted toward the "dangerous" end (i.e. higher magnitude). The more socially threatened one feels, the more the pain response will be shifted toward the "dangerous" end.
Here is a somewhat contrived but favorite example of mine. One night, you wake up to go to the bathroom. In the dark, you unexpectedly step on your child's lego brick left on the floor, and it hurts immensely - it feels like the pegs are actually spikes! This is mainly because of how it has surprised you; the context is that it's dark, you expected the trip to the bathroom to be just a few simple steps, and (for sake of argument) have never stepped on a lego before. Your brain feels rather threatened by this surprising situation and generates a large pain response. Now, a night or two later, it happens again, and though it hurts it definitely isn't as bad. Another night or two later, it happens a third time, and barely hurts at all (you're basically to the point of expecting it now). I think we can agree that no tissue damage has really been done, and if pain was simply a state-of-tissue indicator then the magnitude of pain should have been the same each and every night. Additionally, if tissue damage need be present for pain to be present, why did it hurt at all?
Lastly, I'll note that lack of apparent examples != lack of evidence.