Isn't the solution simple? Pay nurses like 80%-100% of what traveling nurses make, instead of 50% or less.
I don't run a hospital, but know folks who have worked in one. My guess is that paying someone 2x (or many someones) for a short period of time is easier on the long term budget than raising the wages of permanent employees. Feels similar to how every company seems to want senior developer talent, but few will pay for training new senior talent.
Hospitals are often run inefficiently [1]. This leads to a lot of overhead costs. Many procedures in hospitals loose money for hospitals while others make money. Taking care of COVID patients typically looses a hospital money. So, where does the money come from to pay nurses more when much of their work is on patients they loose money on?
[1] https://claytonchristensen.com/books/the-innovators-prescrip...