Or are they? Why not have a manual safety on a Glock, or a Sig (Wait Sig does have them, as does S&W) or whatever polymer wonder pistola you carry. Except Glock of course, cause Gaston won't let you have a choice, right??
If you don't need them, then why does the US Military buy them in the 100's of thousands and insist their Soldiers, Sailors and Marines must have manual safeties on their pistols??
Yes, I know SOCOM buys Glocks and other stuff without them, but how many of us has anywhere near their skill and training?? Damn few.....