Cats have a reputation for being aloof. Still, when you rescue a cat, you expect that it will become your companion. Sometimes that doesn't work out as you intended. You spend weeks or even months trying to coax your cat out from under the couch, the bed, or out of the closet without success.
If your scaredy cat was not feral or of feral lineage, then you should probably have her examined by a vet. She may have an underlying physical problem. If your cat has no physical problem, your vet may recommend a calming medication or a cat behaviorist . However, rescued feral cats or feral kittens, may never accept human companionship.
Those of us who rescue feral cats may tend to think with our hearts more than with our heads. We want to save them from the dangers of the world. Instead, we turn their world outside in. We take them out of their home turf and put them in a cage. We call it a house, but to them it must seem as if we cut their territory to ribbons. In essence, we have taken them out of the forest and locked them into a tree. It may be a redwood, but it is a tree, nonetheless.
As we learn more about the needs of feral cats, we are able to make smarter choices about their welfare. Instead of capturing feral cats, animal advocates catch, spay or neuter, inoculate, and give them their freedom.