When people say it doesn't "work" they don't mean that the victims don't "cave", they mean that the information the torturer gets isn't useful because as you sa

When people say it doesn't "work" they don't mean that the victims don't "cave", they mean that the information the torturer gets isn't useful because as you say the victim will tell the torturer anything they want to hear. Also in movies usually the purpose of torture is to make the victim divulge something we already know they know, like where they hid the treasure we saw them steal in an earlier scene. In real life we don't know if the victim knows anything in the first place - they may be guilty or they may be totally innocent.