How can you demand "treatment" VS admitted for "observation" when dealing with ER / hospitals?

are hospitals in certain areas ER ranked

And medications given during the observation are not covered by Medicare or by Part D, even medications that are part of the patients regular care.

But the Medicare reimbursement if transferred to rehab is different.

Hospitals are using the "observation unit" to help keep patients from returning back to the ER once released from the ER.

Last year I was in the observation unit for 2 days... I was glad I wasn't taking up a bed for a more critical patient.