WHY YOU NEED A TAG, AND WHY A COLLAR ITSELF IS NO HELP AT ALL

Recently, I've helped with 3 lost cats in my area:

1. Freud, an epileptic cat who fell from the 3rd floor window and was wearing a collar and tag

2. Mimi, a cat who escaped from the carrier outside the vet's office and wasn't wearing a collar/tag

3. A cat who was found, who had just a collar (no tag)

1. FOUND AFTER A FEW WEEKS! He found his way to a garden about half a km from home, and was hanging out there for 2 weeks before the person could finally get close enough to him to read the number on his tag. He was returned home safely within minutes, just before a huge thunderstorm!!!! Without the tag, there is no way he would have returned to his owners.

2. FOUND AFTER A WEEK of intensive searching and trapping! Mimi wasn't wearing any ID, but her family did an intensive search and rescue operation and eventually got her home safely when they trapped her themselves! Hooray!

3. NO LUCK :( A few months ago, a little, old, sweet cat showed up near my house. He was wearing a green collar, but no tag. He is currently being cared for in the garden where he originally appeared, but I haven't been able to find his owners, and he cries outside the building to be let in. I'm working on resolving this story, and won't quit until I find a happy ending. The collar his family put on him was totally useless without a tag! Is someone missing him? Are they heartbroken? Or do they even care?