I feel for stray animals, too. If this is of any consolation (which it might not be), it's possible that that cat comes from a line of strays, so it may not know anything else. Also, of stray domestic animals, I think cats have the easiest time compared to stray dogs. Unless the cat looks ill, try not to think of it that much. Regardless, it is people's responsibility to either spay/neuter their cats or think long and hard before adopting one (possibly leading to "release" or abuse). When I lived in Taiwan, the sight of many stray dogs was heart-breaking. As said, they fare worse than cats for various reasons. Many were mangy and often victims of rather horrible demises. It's a rough world sometimes where we must build some figurative calluses else we be depressed constantly.