[gregjor]

I agree that getting something from a recruiter or employer you've spoken to, or emailed back and forth with, seems the polite thing. Having done a fair amount of screening, hiring, and working with recruiters I can give one reason you never hear anything back.

If a potential employer or recruiter (who could qualify as an agent for the employer, because they have a contract) says anything to a candidate they open themselves up to lawsuits (at least in the USA). Suppose a recruiter does call or send an email: Sorry, we don't think you qualify for the job. Or, Sorry, the employer chose someone else. Many candidates will pursue that with more questions -- What did I do wrong? What skills don't I have? How was the other person better than me? That kind of thing. And any answer the recruiter gives can open a can of worms, from negative social media posts to lawsuits.

A person who doesn't want to date you might make up a white lie -- I have to wash my hair that evening, I can't get a sitter for my dog, etc. because they don't want to say "I don't find you attractive." Employers and recruiters can get sued if they tell the truth, and sued if they lie, so they often just say nothing, or send out some generic email like "We'll keep you in our files." Candidates should understand that and not take it personally.

A good recruiter can coach candidates and help them fine-tune a resume and cover letter, but as I mentioned before recruiters will only put that kind of effort into candidates they strongly believe they can place. Everyone else gets ignored.