This addresses only my opinion on one less-central aspect of the question:

I agree that the more extreme forms of what you describe are unethical or immoral.
As well as avoiding mistreatment of the target animal, I would personally never use live-bait for anything, but that's a personal choice and many would be happy to do so.

But I don't see too much wrong with using food as a bait or attractant. This may be meat (bits of dead animals) for Owls or Falcons and bread or grain for sparrows or whatever. The point is that the ethics of the treatment of the target animal and the ethics of the treatment of the bait can be separaed. In my case I'd be happy to use meat which met my standards for treatment but a vegetarian or Vegan may be horrified at that choice.

The photo below is not presented for any technical merit (you just TRY and get a good photo of the about fastest bird on earth :-) ) but because of its relevant here.

This is a NZ Falcon. It lives in a specialist raptor rescue center - birds arrive in damaged condition and stay long enough to get them back to a point where they will probably survive in the wild. This bird is free to do what it chooses every single time they release it - which is frequently. Even when "in captivity" NZ Falcons live on the very very edge of being always genuinely wild. A week or so on the loose and it will not come back. But when fed and cared for it will return reliably.

This one is heading for me not because of my gastronomic attractiveness but because a young lady (one of only 7 qualified falconers in the country) is standing behind me with an unknown piece of dead animal on her gauntlet and I'm an incidental in its path.

Is this ethical? I'd find it hard to see it wasn't (ignoring for now arguments re feeding bits of one animal to keep the latter alive). Is this photo (or any better one that others may manage in the circumstances) less "real" due to the circumstances? [Shame about the fence - I left it in here but it's edited out in other versions]. And, yes, I'd say it's less real - and in the no-fence versions I know the circumstances, even though others may not. If wholly wild it would probably have gone and found a live rabbit that wasn't lurking just behind me.

How far is it acceptable to extend this treatment? of bird or environment. I could set up a hide with non live bait. These Falcons come to a lure swung in circles at speed by their handlers - emulating a live animal. Enough :-)

500mm f/8 Minolta mirror lens (hence the bad bokeh).
Minolta 7D, 1/750s, ISO 800, f8.

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Barbeque Duck: <- on website here, but larger image via image download below.

How does this rate in terms of baiting and training?
The duck is "wild" (or as wild as a Mallard duck can be in an urban environment where they become accustomed to people).
It is free to come and go as it wishes and it spends perhaps 30 minutes to a few hours per day on my property.
The picture is unposed to the extent that the duck was not compelled or led or drugged etc. It is where it is entirely of its own choice.
However, I did influence the choice :-).

Each day in summer we put out wheat and bread in the later after noon for ducks to eat. Typically 3 to 10 duck families breed and raise ducklings on our property each year. There was a BBQ (shown) in our yard and I decided to try to persuade a duck to do just what you see here. Each night when I put out the wheat I would put several handfuls on the BBQ and the rest in the yard. After a while this duck would come to expect that there would be wheat on the BBQ and would go there preferentially. After a while it would settle on top of he BBQ afer eating. Photos happened. So:
Baiting / training / posing / contrived.
Wild, free range, uncompelled.

"Legitimate"?

Right click and download image for 3000 x 2000 version.