Cats and dogs seem to stray the most compared to other animals.
I don't understand why someone's pet would stray.
I do know there are implications when you find a stray animal on apartment building property.
The spread of disease from that animal is a factor because you don't know where it came from.
Sickness that spreads through an apartment building's residents is an unpleasant situation.
Out west, around the Arizona area, a lady will take in any stray animal that finds its way near here home.
I'll agree with you that some animals "get out" and are never to be found again. However, the bigger problem is that people will adopt an animal that they have no intention on loving and caring for like a family member. Too many people DUMP their animals just because a problem arises that they feel they can't afford to fix, or the animal gets "old" and these people feel that the animal is not worth keeping anymore because doggie can't "play" like he used to or kitty went blind and can't see anymore.
Are we not supposed to be the ones with a thinking brain? Animals are not toys to keep your kids entertained while you gab on the phone all day. They're living, breathing, beings that need care and love, just like an infant, and throughout their lives, just like your children. People need to know before they adopt any animal that this is a LIFE-LONG PROPOSITION and if you're not prepared to deal with what may come, you need to back off and NOT adopt AT ALL.
As far as "strays" having diseases, this is, most of the time, not the case. If people are so concerned with the number of strays in their neighborhoods, these people need to get together to find a way to contribute and have these strays spayed or neutered so that they don't reproduce in to unmanageable numbers. There are many rescues out there who will help spay and neuter these animals for a DONATION. Why don't the people of a neighborhood contribute just $5 each and make that donation to a rescue who can help with a stray population? You'd be surprised all of the things you'd learn and learning should be a human being's life-long pursuit. If there's something we don't like, CHANGE IT, but don't expect CHANGE to happen until WE take the steps to MAKE it happen.