You could also describe a human having an appendage chopped off in the same "mundane" mechanical way: loss of fluids, mechanical damage to nerves sending electrical pulses, etc. To some external observer, it's "just" a purely physical process. I'm not sure it's a useful description or perspective.
The point here is that although maybe the mechanism here is just a mechanical process (although, what isn't?), the important thing are the responses to this, by the plant, other plants, and other organisms. Boiling water isn't going to take some action based upon it boiling nor are other organisms.
When you cut off a human's appendage, the screaming comes from a voice. The voice comes from a sort of... consciousness. Which while we haven't exactly nailed down what makes one up, we are reasonably certain that it involves a nervous system.
Making this absurd for a sec to make my point, I think they’re just saying if the physical sound of an arm being cut off just happened to mimic a human voice crying out, that wouldn’t make it a sign of consciousness like an actual “Ow!” from the speech center.
There’s a difference between a creature’s higher level response to a stimulus and just stuff that happens as a direct physical consequence of the stimulus.
It’s the same deal as boiling live lobsters. They aren’t actually screaming, even if you would be. That’s steam escaping. What the plant sound actually is, no clue. But I think the lobster scenario is what was being suggested upthread.
Literally the only difference between the two scenarios are the amount of complexity of the systems involved. You can describe either one in purely mechanistic terms.
It's still just physics and chemistry all the way down though. It's not clear that plants couldn't evolve something similar through a mechanism other than a nervous system.
The point here is that although maybe the mechanism here is just a mechanical process (although, what isn't?), the important thing are the responses to this, by the plant, other plants, and other organisms. Boiling water isn't going to take some action based upon it boiling nor are other organisms.