Ask HN: Talent shortage high expectations, or something else?

I feel like tech job openings lately (not faang) especially "full-stack" roles are something like "we're looking only for unicorn talents for 55k" and this has been the trend for me lately.

I know that these hiring managers from respected companies with Senior Engineering backgrounds would not have such talent expectations.

But I have gotten through one, up to the final stage of the interview. Still, I was surprised when they asked me deep technical questions for any large-scale infrastructure knowledge. I was not prepared because it was not on the job description. FWIW, I looked-up their company and they recently had several rounds of layoffs.

Why have these companies not given up?