If you're asking why there's no manual safety, it's because the modern doctrine for handguns says that it is unnecessary, on the basis that the handgun should e

If you're asking why there's no manual safety, it's because the modern doctrine for handguns says that it is unnecessary, on the basis that the handgun should either be secure in the holster or - if drawn - ready to fire. A properly secure holster prevents trigger from being pulled even accidentally, so if the gun is impossible to fire at all without pulling the trigger (as e.g. the Glock design achieves for striker-fired guns), the holster is deemed sufficient, and manual safety is considered a misfeature that doesn't add safety but makes deploying the gun more error-prone. FWIW this isn't even a new take. Many popular DA/SA guns cannot be put on safe at all when they're not cocked, even though they can be fired through double action - logic here being the same, between heavy trigger pull and hammer block it just cannot fire without a trigger pull. That said I personally don't agree with this analysis. Or, more accurately, I believe that the increased risk from not being able to use the gun when it's needed is not properly balanced against the increased risk from making the gun easier to fire, especially in applications where handgun is not the primary weapon (which is almost always the case for the military).