Again, this setting is not representative of most of our practice environments.
Mostly stab wounds in the UK vs more gunshot wounds in the US (I'm assuming you're in the US). They self-dispatch and perform ED thoracotomy on scene (typically a clamshell procedure). They carry blood products, have ultrasound, etc. On-scene ED thoracotomy is a very highly rehearsed procedure for them. They have well-established guidelines to expediently transfer the patient (by air during the daytime) with a physician in attendance to a trauma center.
Can it be done elsewhere? Sure, if you're in the right area, with the right patient population.
Do you have a surgeon that can respond reasonably quickly to take over care if you get ROSC? Do you have a SICU or something resembling a SICU to manage coagulopathy, hypothermia, give more blood, etc? Or are you at a small community hospital where giving lots of PRBCs to a case like this means you don't have any blood to give to the next patient that needs it?
I would counter that we should use the FAST exam to screen for the extremely small subset of patients that might benefit from ED thoracotomy:
FAST ultrasound examination as a predictor of outcomes after resuscitative thoracotomy: a prospective evaluation - PubMed
Results: Overall, 187 patients arrived in traumatic arrest and underwent FAST. Median age 31 (1-84), 84.5% male, 51.3% penetrating. Loss of vital signs occurred at the scene in 48.1%, en-route in 23.5%, and in the ED in 28.3%. Emergent left thoracotomy was performed in 77.5% and clamshell thoracotomy in 22.5%. Sustained cardiac activity was regained in 48.1%. However, overall survival was only 3.2%. An additional 1.6% progressed to organ donation. FAST was inadequate in 3.7%, 28.9% demonstrated cardiac motion and 8.6% pericardial fluid. Cardiac motion on FAST was 100% sensitive and 73.7% specific for the identification of survivors and organ donors.
Conclusions: With a high degree of sensitivity for the detection of potential survivors after traumatic arrest, FAST represents an effective method of separating those that do not warrant the risk and resource burden of RT from those who may survive.
The likelihood of survival if pericardial fluid and cardiac motion were both absent was zero.
Keep in mind this was done at a high-functioning busy trauma center in California, the kind of place where the in-house trauma team responds to the ED immediately. Not a community hospital where your general surgeon is at home in bed and takes 5 minutes to call back and then 20 minutes show up. 3.2% overall survival, in an ideal hospital setting (academic level 1 trauma center).
Out of hospital arrest with no pericardial effusion with no cardiac activity? No thoracotomy.