> I don't have the same standard for what is "reasonably-provable ability to actually care for a dog" that dog rescue volunteers tend to

That is indeed the problem. The complaint here seems to be that your standards are lower than theirs. That doesn't always mean their standards are too high; it could very well mean your standards are too low.

> I don't think they are better qualified to determine that

These people are (hopefully) trained specifically to determine that. It's possible you might happen to have even more training or experience in that regard, but most people don't.

> their attachment to the dogs

If attachment was the primary factor behind them rejecting your applications, they'd adopt outright (which does happen) instead of wasting your time. I suppose it's possible that they might have to have a certain number of rejections from the general public before volunteers/staff are eligible, and similarly possible that there are volunteers who don't qualify to adopt (though I'd question whether they're qualified to volunteer).

Most volunteers and paid personnel with whom I've interacted seem to be painfully aware that they can't take in every animal in need, and thus have to take comfort in animals going to good homes. Keyword there is good homes, though.

> Many rescue organizations even buy dogs directly from breeders.

That'd be surprising, since it makes no economic sense. It's possible (probable, even) that breeders might be discarding dogs they can't sell (this is how my mom got one of her two beagles; she couldn't get pregnant, so the breeder was trying to get rid of her), but buying healthy salable pups is unlikely (and in fact would now be illegal in California, per the article that catalyzed this whole discussion). Not to mention shelters tend to be overcrowded as is; outright buying more dogs is only going to make that worse.

I mean, I'm sure it's theoretically possible, but that seems like the sort of extraordinary assertion that would require extraordinary evidence.

> I guarantee you rescue organization volunteers aren't using risk models to adjust the difficulty of their interview processes.

I can't speak to all shelters, but at least from what I've seen there tends to be some kind of rubric for evaluating whether or not someone is suitable to adopt a particular dog, probably baked into the actual application (and/or the application gets fed directly into that rubric). There's probably room for bias, but it ain't like it's the wild wild west, either.

> Dogs in kennels spend a lot of time alone in cages. Moving to a new home in most cases, the dog will get more attention, not less.

They also get a fair amount of time not alone. At the very least you have volunteers walking the dogs daily (or more!). That's usually done with multiple dogs at once for efficiency's sake.

> they don't know what the average case is.

I'd imagine there are relatively few animal shelter personnel (paid or otherwise) who haven't themselves already raised animals in any capacity.

> They only see the results of worst case scenarios

And their primary job is to prevent those worst case scenarios from happening again. If the people who always see worst-case scenarios (and who are either trained or in close contact with those who are trained to identify worst-case scenarios) think that you raise enough red flags to look like a worst-case scenario, then is it possible that maybe - just maybe - they ain't wrong to be hesitant in letting you take home a dog?

That's not to say you're a bad person or anything, or that you're incapable of properly raising an animal (it doesn't sound like either of those things are true); rather, there seems to be something beyond "being a normal human being" that is raising a red flag. I don't know enough about your specific situation to know what that is.

It does sound like maybe you've had a bad experience at a particularly-strict shelter and are extrapolating to shelters in general (and to be fair, I'm probably doing the same with my own experience with shelters). Or perhaps you just happened upon a time when particularly-strict volunteers were on shift. A different time or place might help; not all shelters are going to be so strict about things (especially kill shelters; given the choice between a suboptimal adoption situation and killing a dog, they'll probably choose the former).