"You were sufficiently promising to pass our screening but after meeting you we can definitely do better. Have a nice day." is not an easy thing to say even in absence of legal issues. I could tap-dance on your face as an employer without getting sued here, but that doesn't mean we sent applicants home with a list of their inadequacies.

Of course, if you believe social science research, the reason is probably "You failed in the first five seconds to connect with your interviewer, he rejected you then, and he eventually found a reason to hang his hat on."

Sometimes they can't tell you the actual reason. Maybe they are suddenly having cash-flow problems and are actually thinking about laying people off.

It can be hard enough to get honest feedback from your friends, throw in legal liability and there's very little incentive for a potential employer to tell you exactly why they didn't hire you.

Getting _real_ feedback on anything you're doing is probably one of the most valuable inputs you can get. Depending on the context, such as applying for jobs, it can be really hard to get. At my last company I gave a few applicants real feedback on their resumes _if_ they asked for it (very few do). As much as you want to tell a person who doesn't work for you but can still sue you how they can improve, it can be hard to justify the risk.

I feel like in some circumstances there's a tendency to interview people even when they aren't that seriously interested in hiring them, which isn't exactly fair to the applicant. I wish people would be more open about this when it is the case.

Well I tried that once, on the basis of 'treat others like you want to be treated', so I listed the mistakes she made in her job interview at the end so that she could improve on those points in her next interview. I wasn't being an asshole about it, I did it very carefully, it was a very hard thing to do because I'm usually very nice to everybody, it's second nature to me to not ruffle any feathers, I really framed everything in objective terms, made sure to tell her why I did it etc.

Next thing you know I'm sitting there in the conference room with a crying girl, and I'm not talking a silent tear crying, I'm talking full-out wailing in a way that the secretary from another company 2 doors down (!) came to check up on us, to see what was going on. So I come out like a bumbling idiot trying to make up an excuse for what was going on to that secretary, trying to calm down the girl I was interviewing, and she probably still went back home telling everybody what a heartless bastard I was.

So now even when people ask I'm very careful to phrase any feedback in the most general terms. It sucks for those who could handle the honest feedback, and I hope that others that I will interview with in the future are braver than I am, but this 'giving honest feedback' hasn't worked out for me.