Clearly, some still do not understand how this works. Let's try again.
Blindey, yes, we took the job knowing that we would see some nasty stuff, but does that mean that we want to see nasty stuff? I can assure you that all of us have seen things that we will never be able to forget and I can also assure you that, given the choice, we would rather these situations not occur. We will respond nonetheless, but we'd prefer that the accident never happened in the first place. It can be emotionally taxing.
Buck O Five, we as fire and EMS can pronounce someone DOS; however, that does not remove the need for a fatality investigation by the police and body removal by the ME.
And lastly, MouthBQ98, who has clearly never dealt with this type of situation before. You do not simply show up, scrape someone off the ground or out of the car, load them up, and call it a day. Fire or EMS declares the patient dead, the police must launch an investigation - which requires measurements, photos, diagrams, etc. - the fire department must cut the victim out of the tangled mess, and the wreckers must clear all vehicles and debris from the roadway. This takes time and the reason that the entire freeway is shut down is so that the responders don't have to worry about someone else plowing into the scene while they are working. You said something about no lives being at risk any longer (after the patient is declared dead), but you need to understand that the responders' lives are at risk the entire time they are operating on an open freeway. This is the reason for the closure and you can be damn sure that I will shut the freeway down to protect my guys from that risk.