I may be a bit different because I don't work in house and work for multiple clients but when I get asked for feedback I give honest feedback. Honest and constructive. I am also sensitive to people.
So if I am not delivering the feedback personally I give the information to the person who is, in the most honest way. For example I have had to give feedback like this before:
In the group activity X's manner was quite abrasive and occasionally almost aggressive which meant he did not collaborate well with the group. His confrontational approach (where he interrupted, talked over other candidates and raised his voice on three occasions) meant that he didn't get all the information needed to make an informed recommendation which was the main requirement of the brief. At one point he held his hand up in another candidate's face while she was speaking and said "I am going to correct you there. The most important thing is not what the client wants but it making money for the company. If that means telling a little white lie than so be it.". This raises concerns not just about his people skills and ability to influence and engage with others which are essential skills for the role, but it also suggests that he lacks integrity which is a core requirement when working in a regulated role.
However, the person delivering the feedback (and sometimes that is me) would frame it differently for the applicant and of course it would vary depending on the type of role and level but for a trainee role this is pretty much how I do it:
In the group we had some concerns about how you presented your arguments and felt that you didn't gather enough information from others which meant you didn't make the most informed decision. I don't know if you realised that you did this, but when you were making your points you sometimes talked over the other candidates, raised your voice and at one point you put your hand up to stop another candidate speaking. Unfortunately this meant you didn't engage with others in the group which was a key part of the task. The panel felt that you could improve by changing your approach to be less confrontational and more collaborative. As a trainee integrity and honesty is very important so while you are right that as a firm we need to make money, we felt that "telling a little white lie" to clients suggests that you haven't quite grasped the professional expectations of the role and you need to do some work on your understanding of the ethical and regulatory requirements.
All candidates can request copies of any written assessments and feedback so nothing is secret. Legally you can request information related to you by making data subject access requests from any organisation holding your data so that would apply to employers you have applied to.
And ime everybody wants to know what is happening with their application because it may have a direct baring on whether they apply for other jobs or decline/accept other offers. The only people I have come across who don't care if they hear back or not are those who have to apply for jobs whether they want them or not as part of mandated requirements for those claiming JSA (NB not all JSA applicants, just those who are forced to apply for any role regardless of suitability and those who don't actually want the job). They are very rare.