Because the moment they send all first responders in without waiting out any secondary devices and they all get blown to bits, they'll then be dragged the opposite way across the coals.
They can't win because the public/people not involved have no appetite for anyone dying, they want magical responses where everyone one ends up ok.
It's not about "winning" its about saving lives in the best way possible, and that means using risk management and having to actually take a risk, something these people are seemingly allergic too.
Also, you don't send in "everyone", but you send in some (say 2 units) and keep a constant stream of that "few" moving in and out i.e. as 2 get in, collect casualties and leave, another 2 immediately move in - then repeat whilst listening for the go-ahead from the Police who clear the scene for you to send in more units, but don't hold EVERYONE back "just in case", thats been 100% proven to have led to extra deaths at every inquiry we have again and again.
Again, I'm ex-military, I know the Risk vs Reward of getting medics into mass casualty events within the Golden Hour and I think there's too many people at the top of the management chain who either freeze up in the stress of the moment, or are spineless cowards who are more concerned with "not making any decision" rather than saving lives. So they pass the buck further up the chain until someone somewhere eventually is forced to order them to do something hours later, rather than doing their jobs immediately, assessing the risk and decided that the risk to some units is worth the benefit in saved lives.
How many extra lives are we going to accept being lost because time and time and time and time and time again Medics are held back outside the "Golden Hour" by a management chain that will NOT take any risk at all?
Edit - I also wonder who many of the "Hold back, thats the rules" people on here have any experience or training in mass casualty events, or how they'd feel if it's their child who died and at the inquest they found had died because the medics were blocked from attending whilst their child bled out?
I also realise that I probably sound overly passionate (or angry to some) about this. We trained for mass casualty at least once a year and I've personally experienced it twice, so when I see it being done so badly and lives being unnecessarily lost because of it despite management claims that they "learned lessons" from the previous 4+ attacks, I feel strongly about it.
