Last time that I went to the ER for a CT of the brain, following a car crash with significant symptoms, It took over 6 hours before I was scanned and released. This was on a "slow" night of the week. I had a headache and was between a little child that screamed the entire time and an old man with dementia, that screamed the entire time.
If there is only one or two scanners, well it will take hours before being scanned as emergencies must go first. And if the patient is "well" to complain about their treatment or to be discomforted by waiting, or for that matter aware of the time (eg. conscious), then they are probably not the worst emergency in the ER ...and they are going to wait.
It also does not make sense to transport a patient until the scanner is ready for them. Sure, they could transport him but then he would be waiting in the mean time. And those gurneys are small, and CT scan is usually cold.
And were you sure that those were nurses talking outside the room? They could have been techs/aides, phlebotomists, residents, interns, respiratory therapy, social work, EMT/paramedics, transport, dietary, housekeeping, engineering, patient reps, chaplains, physical therapists, students.
For that matter, if they were on break and CT were occupied, well yes they needed to be in a breakroom, but as someone that works nights, and has no relief, our nurses frequently have to eat and "break" at the desk..because we have no choice. And on a 12 hour shift, you better hope that we eat something so that we do not pass out in a code. Unfortunately sometimes we don't even get to eat, or even pee, even though we will always be docked for the break time.
I regret that the "service" could have been better. But ER care is not about service, it is about getting the worst cared for first, and the rest as best you can and just keeping people alive.