It may be a qualification gap. E.g., they need a welder, but people these days don’t learn those kinds of skills.
Also, from what I remember of job postings, they ask for a large number of things to see what they get. I suspect a lot of people look at those and go, “Oh I don’t meet those qualifications, I can’t work there”. A friend of mine got a job where one of the quals listed was a PhD, but he only had a bachelors. He decided to apply anyway and it turned out the company did had the opening for 8 months and was close to modifying their qualifications.
Bull, I can find a welder at $100.00/hr tomorrow. Can I find one for $10.00/hr, no. So the trick is to find the price point between $10 and $100 that attracts the qualified welder. It isn’t rocket surgery.