Safe staffing?

I am an RN in an acute psychiatric, for profit hospital. I love my job. However, nurses and management seem to be in constant disagreement about what constitutes "safe" staffing. I went to work briefly in long-term care, in a not for profit facility, just to see how different the staffing practices were. I found the same issue - too little staff (nurses and aides) to ensure a safe milieu for patients and staff. I understand that facilities are concerned about their bottom lines, however, it seems really short-sighted to limit staff in order to save money. My question is this; can any nurses here tell me that they work in a facility that staffs appropriately not just based on census but on acuity, as well? Of those that feel safely staffed, do you feel that, as an RN you have a voice in the staffing decisions?

PS. I'm still pretty new to the nursing world (3 years). I have also been a self-employed massage therapist for 23 years. There are many things about working for corporations that confuse me.

Thanks all.