Why do some companies keep posting the same job ad over and over, rejecting everyone who applies, while at the same time saying they're in a tight spot and desperately need people?

About two years ago, a large company sent an engineer to our university's career fair to talk about job opportunities at their new office in a remote location, where they hadn't been able to hire anyone for about 8 months. They were specifically looking for new graduates and junior engineers. The engineer seemed like he was going crazy and would hire anyone. He kept saying they had tried all recruitment methods, like ads and offering more money, but no one wanted to go live in that remote area. The nearest small city to the workplace is about an hour and a half away, so the location was honestly shit, to say the least.

I got excited about it because I didn't have strong ties to the city where my university was, and I had about two months left until graduation, not to mention that getting your first job is the hardest thing to find. The engineer gave me the details and I applied right there on the spot, but a short while later, I received an automated rejection. I tried to contact the engineer again, but he never responded at all, and frankly, it was disheartening.

After I graduated, I found the company was still advertising the same job for graduates, but they had put up a long and extensive list of requirements. Even though the requirements were many, I applied again, but I never heard back. A few months later, I saw the same ad posted again, but this time they were asking for an entry-level engineer with 2 to 4 years of experience. I applied anyway, and as usual, no response.

When I talked to my friends who graduated around the same time, it turned out that a few of them had the exact same experience and were being ignored by the company. Fast forward to now, I've found another job, but it's not going so well, so I started job hunting again. While searching, I found the same company is still posting the ad for this same job, which has been the case for two years now. I'm honestly confused and don't understand why they're doing this, rejecting people who apply, and also raising the requirements, while at the same time saying they're in a tight spot and urgently need someone. It makes no sense at all, and I'm curious to know what the purpose of all this is.