Bump....
Two or three cats is a good number to have if you live rural. One in every human lap, and they keep the number of rodents down. But sometimes an animal in need drops from the sky, as it were. Abandoned kitten, thrown out of a car by some bad person (there should be a special place in hell for those that dump kittens in garbage bags in roadside ditches), or left to its own devices because its feral mum died. You pick it up, save it, give it the medical care it needs (including sterilisation) and then either you find it a good home elsewhere or adopt it.
So at the time of writing, we have seven cats... all saved cases. All neutered, vaccinated and with their own passports. But we live in a rural place in France with very few neighbours and some terrain of our own. Without our cats we would have a far more serious rodent problem, especially mole rats that destroy veggy gardens and can even kill (fruit) trees by eating their roots.
If we had taken in every abandoned kitten we saw we would have had twice as many, but we helped find good homes for other cases.
Most of the 'cat problem' is a human problem, of people who 'keep' cats but do not neuter them and abandon/dump the kittens that are born - or just feed ferals without taking the next step of getting them caught and neutered.
If the cat in question behaves more like an abandoned housecat than a true feral/wild one, best try to capture it, have it checked for an ID chip by the vet and if it does not belong to anyone, decide if you want to adopt it or find it a good home elsewhere. But in any case, arrange to have it neutered.