I've been rejected before by companies that gave feedback, and I remember some of them pretty fondly. There was one in particular who sent me resources and suggested books and projects I could work on while I was self-teaching. To be clear, I don't expect everyone to go that far out of their way, I just expect a modicum of humanity: do a proper phone tech screen so that we don't waste each other's time, and give me some specifics about how it wasn't up to par -- especially if I tell you I'm a self-taught candidate and it's clear I spent a lot of time on your process.
Anyway, something I've learned both about prospective employers and relationships in general is that if someone takes an adversarial approach to any relationship, especially when there's a power differential that's not in my favor, it's worth steering clear. In the case of prospective employers, it's pretty much always a sign that I'm going to be treated like pure utility and not much else.
Certainly all employers should provide an initial phone screen before requesting that a candidate do some kind of work including presenting or traveling. Or even doing take-home work if they still do that sort of thing, though I'm glad to see that becoming less common. I would consider it rude and unusual for a company to do otherwise.
I'm solely referring to offering to rejected candidates the opportunity to discuss specific critical feedback about what factors contributed to us turning them down instead of the standard boilerplate responses like "we went with someone with more relevant experience".
I'm not sure whether you consider declining to provide critical interview feedback to be taking an "adversarial approach" but in my experience it is extremely common.
In most cases a followup call really is rewarding for both parties, and if I have some social connection to the candidate I still offer it. And even when I don't I still sometimes do it despite reservations. But after having candidates become argumentative and having a coworker get burned by a litigious candidate I'm more wary of spending the time and incurring risk as a general practice.
If I was running my own company then I hope I would go back to offering a followup call because I think it engenders goodwill and the overall utility vastly exceeds the risk. But at a BigCo my risk/reward ratio is different. If HR and Legal get involved it doesn't matter how meritless the accusations are, everyone is about to have a Bad Time.
Anyway, something I've learned both about prospective employers and relationships in general is that if someone takes an adversarial approach to any relationship, especially when there's a power differential that's not in my favor, it's worth steering clear. In the case of prospective employers, it's pretty much always a sign that I'm going to be treated like pure utility and not much else.