I generally agree with on this one more than with OSC. But for the sake of argument, what should be said is that the problem is not that you'd get too little info from the subject, but too much. And when you can't verify it, too much info can be as bad. How to tell where is the truth and where is simple desire for you to stop the pain? What if there are multiple layers of the truth?
It may be that with our society aversion to torture, we simply don't have specialists good enough to tell.
The question assumes that interrogators are stupid. Anyone undergoing torture is made well aware that should their information prove inaccurate, that another attempt will be made to get the truth. Why lie, if it only means you will be going through it again? Generally, what information is gained, proves true.