When I'm nervous, my brain can clamp up.
I remember being asked to name the steps of the graphics pipeline once, after a series of whiteboarding questions. The men in the room stared me down, while I tried not to shake near the whiteboard. I clamped up. I felt myself sweating. I know this, I had built several successful apps and done a lot of graphics work. I wasn't a newbie, and some people really respected my work. But all I could think about was not looking stupid and how they were all staring me down.
When I dig into a problem and really do my best, I need to be totally calm. Even basic things can become very difficult when I'm panicked.
And then, other things come into play.
I remember walking into an interview and being asked by someone who did not know me, "Hey, what are you interviewing for? Do we have a designer position? ... Oh, low level graphics? ... Really?!" Looking around the room and only seeing men. I knew they didn't think I could really code. I knew they were giving me a harder time and assuming I knew less because of my gender.
Clamping up intensifies.
When your expectations of someone are very low, sometimes they feel that and become even more nervous. And then they appear to confirm your bias.
In all the times I've really shined in my career, it's when people have taken it as a given that I was very intelligent. Gave me a question and fully expected me to be able to answer it even if I stumbled, made me feel like I could do it and shouldn't give up, made me feel totally calm and respected and confident. If I couldn't figure something out, assumed I still knew my field, asked different questions, gave me time.
Less technical grilling, more curiosity and open mindedness. Less disappointment at the wrong answer, more wondering what else they know that you might not. More giving people time to think, being socially aware and recognizing when people are nervous and giving them an environment in which they can be calm.
When I hear "No good candidates apply!" I think of these above points. I think about how I've definitely been that "bad candidate" in their eyes, and now I'm doing just fine.
I think about the people who rarely speak up in conversations. I think about why certain people are assumed to be smart and competant.
You might be the one who is wrong. They may know much more than you thought. They may be used to people thinking they're stupid, and need patience, and need to see that you will be nice people to work with.
I believe especially for junior roles, probably 90% of people you interview can do the work just fine. I believe in group discussions, many competent people sit on the sidelines because of these patterns.
Stop being so critical, and start thinking of what you can learn from people.
One of my favorite pieces related to this: