Why have I not heard from anyone after applying for a job , not even an acknowledgment

It's an apparent disrespect to the applicant. I always asked for feedback on why I didn't get the job.

It happens all the time, it really is normal, annoying but normal. You can reach out to HR and check on the status, some HRs actually like that. Keep applying, do not get discouraged.

While irritating, it's not uncommon to receive no reply to an application unless the employer is interested in interviewing you immediately. I'm a dinosaur who began nursing many years ago and a reply was always sent - either they wanted to see you, or they "had nothing your qualifications meet at present". Those days are long gone. You should know that hospitals may keep qualified applications on file for up to 3 months, six in the case of specialty units. Just because you have not heard right away does not mean you will not be contacted when a position opens in the near future.