In both cases, human mind keeps circling on what went wrong. Is there any misunderstanding or wrong perception? So providing reasons is humane in any such life altering transaction.
Related to law, is following possible?
Before interview, there will be an agreement needs to be signed by interviewee, recruiter, company involved, so that, after interview, recruiters can provide reasons for rejections and as long as the reason is with in the laws of the country or appears reasonable, then involved parties will not proceed legally. If it is against the law, then interviewee may proceed legally. It may be expensive but we are not robots, right?
Different cultures have different opinions on work/job/career...etc. Since Americans are advanced in technology as of now, many countries are adopting similar policies and during that process, workforce management related laws also getting copied. These laws may be new to that society and difficult to understand by society/family. This makes lot difficult to effected employee to explain the rationale, which he/she also do not know. People won't even believe that reasons are not provided.
In conclusion, providing reasons or at least honest effort in that direction is needed, since we are dealing with other human beings rather than robots.
You don't need to sign an agreement: this is the status quo. The meat of the problem is when the candidate and the company disagree about what happened. It's a rare company that actually furnishes candidates with illegal reasons for rejection, so it's up to candidates if they believe they were illegally rejected.
I agree, signing a document is really stupid and unnecessary.
What I mean, if you give someone a reason, it can lead to it looking bad on paper. Unintentionally. If you don't give them a reason, you protect yourself.
Unfortunately, the government puts strict limits on the purview of contract law, so an agreement like this would likely not hold up in court.