Who's to say that companies do not also ask those questions while you are there ? I am a manager at my current company, we regularly ask feedback to employees.

Who's to say that companies do not also ask those questions while you are there ? I am a manager at my current company, we regularly ask feedback to employees. Partly thanks/because of this, we have a very high employee retention rate. But we also conduct exit interviews when someone leaves. In my experience, exit interview yield good result if the employees leaves on good terms, and if he tends to be a bit "secretive/corporate" during his time. If the employee leaves on bad term, you get nothing, or nothing of value (just "rants"). If the employee was already outspoken, you get a repeat of what he already said in the past. But once in a while, you get plain and honest feedback that an employee didn't really "dare" to give while working, by fear of (real or made up) repercussions. People are taught to "play the corporate game", keep to themselves and not make too much waves. For some people that also means "not saying what they really think", unfortunately. Being in a position where they are gone anyway and are off the hook can sometimes liberate their voices. And that feedback is extremely valuable because it's so hard to get in any other way.