Physicians make the decision to intubate in most hospital situations. Deciding to have something done and doing it are two entirely different things. Sometimes there are protocols in place for certain emergency situations, but generally the physician is making the call via phone if it's a boonies hospital, or directly if it's a regular hospital.
I really don't think you understand the realities of health care practice and time management. Let's look at a small hospital that has one physician working the ICU per shift with no resident support and two midlevel assistants that work opposite shifts to one another- one works with the physician during the day, the other covers at night. This setup is utilized at a one of the community hospitals I trained at. Now, a physician is on call during the night but not physically present in the unit the vast majority of the time after 7 pm. This hospital has no anesthesia staff at night, no surgical staff at night, and two nocturnists that keep things running smoothly for the entire facility, one in med, one in surg, with a few midlevels helping out. The ED is staffed mostly by midlevels, with one physician present to make sure everything runs smoothly. Place is well over a hundred beds and most of the time you've got all of three physicians in the building at night that aren't in the ER. So you've got 3 physicians in the whole facility, and you want to drag one of them off to intubate? Truthfully, they have more important things to do, like manage the little emergencies that manage to pop up during the night, keep people stable, etc. The whole night for them is putting out fires left and right most nights, it sucks.
What they decided to do was create a team with an RT, RN, and PA/NP to do night intubations. Intubation is a skill, and the more you do it, the more proficient you get at it. One RT that has done every intubation on nights for every shift he's worked over the last ten years is better than a doctor that does a quarter of the intubations on a given shift for the last ten years, basically. Physician makes the call, midlevel oversees the procedure, RN pushes the drugs, RT places the tube. Since the night shift is really small, you've got a consistent team that's doing basically every single procedure. It works well for the hospital- a whole lot better than dragging off your only surg physician to do an intubation while 8 patients need their attention.