The idea that you can train yourself to never make a mistake and touch that trigger when you didn't want to is laughable. And if you're that capable, training yourself to flick the safety shouldn't be a problem.
The idea that you can't count on yourself to respectfully and safely handle a weapon with a 5# trigger and decent length of pull is laughable, and if you are so irresponsible then who's to say you'll remember to engage the safety anyway.
I mean as long as we are going for hyperbole we might as well flip the script, right?
So I guess you have it all figured out and you'll never make a mistake. Good for you.
Or, here's a thought, perhaps I learned from past mistakes and have trained in processes that will help mitigate any possible mistakes as much as possible. Of course anyone can make mistakes, that wasn't even the thrust of your original question.
I also use a single clip holster and holster off the body, no chance of something snagging on holster (the source of Glock leg) and then after holstering, and here's a key most NDs seem to be derived from, LEAVE THE THING ALONE during the day.
I have no problem with thumb safeties, carried a 1911 plenty and a Ruger SR9 some, I just don't think they are needed for a CCW if you take basic precautions and treat a loaded weapon with the respect it deserves.
If someone is consigned to the fact that they will be unsafe and make avoidable mistakes and therefore depend on a mechanical safety to protect them, I think maybe they need to rethink their philosophy on gun handling, there are other ways to mitigate.
But then again, if it makes them feel better and they train for it, more power to them. I'm not here to tell them they are doing it wrong, I'd appreciate the same in return, but it's often not reciprocated.
I carry a DA/SA, by the way, if it's even relevant.