What I was trying to get to the bottom of was, in a nutshell: Why do the military (and also some fed agencies) seemingly distrust the "striker fired / no external safeties" approach while the same works so well for hundreds of police departments?
I'm not fully sure that such is the case. Even some PDs manage to issue contract proposals that may specify hammer fired guns or are ultimately written to give extreme preference to what the PD was wanting to buy anyway (but they have to have a "competition" even if it's just in name only). It seems more to me that the hammer vs. striker argument is a red herring. So long as the primer ignites, why would one care what gun A uses vis a vis gun B? There's advantages and drawbacks to both ways.
The most direct answer to the question posed in your thread title has pretty well been answered- it was not part of the original competition and since then there has not been shown to be enough of a benefit (vs. the costs involved) to justify reopening the issue.
As for what so and so unit/department uses and why, I think gun enthusiasts tend to get WAY too wrapped up in it. I don't really care if no elite unit uses what I have on my hip... I chose my own gun with an eye toward criteria that matter to me... criteria that do not apply to people kicking doors in non permissive environments. They did the same when they chose their sidearms, and they did so using criteria that don't apply to an overweight desk sitter in middle America.