A few big differences though. One being in addition to having a physician close by IF needed, they also have other experienced ICU nurses, RTs, NPs and PAs, a pharmacy, Hospital security, are in a safe well lit climate controlled indoor setting where family can quickly be ushered out of the room, where weather and traffic isn't a factor and transport decisions don't have to be made, where the patients medical record is usually on hand and their medical problems and history are already largely known.
I want to help you understand a little about the ICU that you haven't gotten to understand in your career as a PCT/volly MFR with a year of ED tech and medic school. I don't mean that as condescending, just that your career hasn't provided you with ICU experience to contrast with your fledgling view of paramedicine.
In the 911 emergency patient, there is usually an algorithmic or semi-algorithmic approach to 1 maybe 2 major problems with very limited treatment options aimed at stabilizing and transport, because that is all you can do with limited knowledge of the patient and typically short periods of care.
Yes, in the ICU, there's the availability of an intensivist, a RT, a pharmacist, a RN, and specialists and imagery and lab and... but 90-95% of the time it is just the assigned ICU RN.
The reason you need those extra resources in ICU is because compared to 911 EMS, the ICU setting is definitive care addressing more complex patients with multiple complex problems in more complex ways over longer periods of time covering sometimes multiple critical periods. (We won't distract by talking about procedural care). The paramedic does not deal with those complexities. If the RN only had the paramedic's limited formulary, they would have less use for an ICU pharmacist. If the RN didn't have to run 12 drips, the pacer, the IABP, CRRT, and read the PA cath, they wouldn't need the RT to help with the vent (there is little most RT do, apart from intubate, that the ICU RN doesn't do).
Yet you see these resources and assume that the ICU RN couldn't hold their own in the ICU if the other providers were busy. What you haven't thought about is that situations occur all the time that put the ICU nurse on their own in bad situations longer than you might think, longer than the transport time for most urban EMS. Here, they have algorithmic solutions to sudden emergency situations just like EMS.