I've been rescuing animals for over forty years now: mostly cats, because I'm so allergic to dogs :(
When I started taking in abandoned pets in the 1960s, I thought how wonderful it was that I could rescue the poor little kitten I had found. I thought that if everybody would rescue just one abandoned animal, things in the animal world would be very different.
I still think that. But what happens is that most people turn a blind eye to the suffering animals, while a few of us go broke and/or have nervous breakdowns because we get so overwhelmed by the number of animals we wind up being responsible for. Luckily I spent many years working for no-kill animal shelters, and I was allowed to bring adoptable animals there. That was wonderful, and helped me (and the animals) more than I can ever say.
But then there are the 'unadoptable' animals: the animals that have some 'defect,' no matter how major or minor, that the general public just doesn't want as part of their household.
I had a very-much-loved cat once who had been abandoned when his owners moved. He was approximately 12 years old, and lost a leg in an accident. Of course he wound up with me, and I loved him tremendously. Another time my friend and I found a small kitten living in the parking lot of our apartment building. We took him in, only to discover that he was blind in one eye, and the side of his face was misshapen. When we took him to the vet, she estimated his age at 10 weeks, and said it was an injury that had injured his head and blinded him--and the wounds had healed by the time he was 10 weeks old! Both these cats wound up at our home, and lived long, wonderful lives. I;ll just never understand what would motivate someone to move and abandon a 12 year old cat, or kick a tiny kitten in the head with that kind of force....