They are not wild
The dogs on those streets are not a wild species that wandered in. They are somebody's dogs, and somebody's dogs' puppies, generations deep. They know what a hand is. They know what a door is. That is precisely what makes them so easy to abandon and so easy to rehome.
The arithmetic is simple and merciless
One unsterilised female, one season, and a corner that was manageable becomes a corner that is not. Nobody decides for it to happen. It simply compounds, faster than the kindness on any one street can keep up with.
Somebody is already feeding them
This is the part outsiders never expect. In Istanbul there are people who go out every single day with food and medicine, paid for out of their own pockets, for animals that belong to nobody. One of them kept Doccio alive for months while he waited to be old enough to fly.
Those people are not the problem. They are the only reason there is anything left to rescue.
Why a puppy in the street stops being shocking
Because it is Tuesday, and there was one yesterday, and there will be one tomorrow. The mind protects itself. A dying puppy in the street is an ordinary sight there, and that is the part I could not accept.
What actually helps
Not outrage. Three unglamorous things: a roof over the ones already rescued, food that arrives every day without fail, and homes far enough away that the arithmetic stops.
We do the first two with whatever comes in. The third one is the part only you can do.