Stray dogs do survive if they find food and shelter, but obviously, their longevity and health are worse off than domesticated dogs. Stray dogs might not be as dependent on humans as tame ones, but they are still, to some extent, used to being around humans. Stray dogs, at one time, were also house pets, who were given meals without hunting and bed without having to fight for it. So, it can and will still be challenging for them to survive in the wild but not as challenging as the domesticated dogs.