Do you ever wonder..

Not really.

Hospitals are huge employers, I once worked at a small 200 bed community hospital that had 2,000 employees. When you factor in normal turn-over with retirement and there rest there needs to be a steady influx of new grad nurses and new nurses in general. That same hospital had an annual turnover rate of around 10-11% every year, not to mention the 20% seasonal influx.

Also figure that the majority of hospitals are not in the large metropolitan cities but are spread across medium to small cities throughout the country while schools tend to primarily focus in large metropolitan areas. Also keep in mind that schools do not churn out as many students as one would think. Most having a graduating class quarterly at most? Maybe faster for small private schools. Graduating classes being as small as maybe 10-15 or as large as a couple hundred for really large schools?

That makes sense! Thank you for explaining that to me, because I have always doubted my manager, at my previous place of employment, when she said the positions were "posted", but haven't had any applicants...