Why can't I seem to get a job with Kaiser or Sutter? I've applied numerous times and have a good work hx.

I've been applying now for a few years for a position as either a receptionist, unit worker, supplies worker, office assistant and I have a great work history and references but Kaiser or Sutter have never called me for an interview. Is there something I could be doing wrong? Or is it true that they hire from the inside? I don't know if I should just give up or keep going because I'd really like to work for a hospital.