If you are going to carry a gun with a safety, you have to train with it to the point where manipulating the safety is something you do without thinking. Back when I carried and competed with a 1911, I was trained to lower the safety on the draw. So by the time my gun was up and on target the safety was off without my ever thinking about it. Holstering was a far more deliberate affair -- bring the gun back to my chest, verify safety on, then holster. I understand that for LEOs that they may need to holster more quickly in order to go hands-on, but that's a pretty unlikely scenario for those of us not in law enforcement.Most people have never trained to the level of stress that's involved with actually drawing a firearm. More than once in my career, the event started, I looked down and my pistol was in my hand, no recollection of drawing it. That's the level of stress you encounter. Some guns, like 1911's, have a very natural safety deactivation, most don't. Are you going to manipulate the safety under that level of stress?
I agree with you that most guns that have safeties do not have a safety that is as easy to use as a good extended 1911 safety (the original, milspec 1911 safety is too small to easily keep your thumb on it while shooting).