The 1911 was originally designed without a thumb safety. The US Army wanted the feature, so it was added. You can visit the museum in Ogden, Utah to see the original prototype if there is any doubt about this.
The Tokarev was a made-for-combat copy of Mr. Browning's now famous pistol. It lacked a "safety" device of any kind.
If you accidentally disengage the safety while holstering/unholstering the weapon or forget to engage it before re-holstering, what's the difference between a weapon with or without a thumb lever safety?
If you can't remember to take your finger out of the trigger guard or permit things that might actuate the trigger to come into contact with it, then you're really not increasing your "safety" (mythical concept, but apparently very real to some people).
Putting a mechanical device in a pistol that changes its manual of arms and method of operation is inadvisable, but I'm sure that won't stop anyone from doing it.
I stopped worrying about thumb safety levers after several experiences driving with a 1911 during which the lever was disengaged. Luckily, the pistol remained in the holster, the leather holster was pretty stiff, and nothing came into contact with the trigger. My takeaway from those experiences was that having a rigid holster that completely covers the trigger is a really good idea and if your thumb safety works properly that's great, but don't count on it.
I carry a Glock now, use a kydex holster, and before I re-holster the pistol I make sure there's nothing obstructing the holster. If I can't trust myself to take prudent precautions to prevent a ND, like not pulling the trigger unless I intend to fire, why should anyone else trust me to carry a gun?
If having that little "safety" lever there is more important than having a weapon that goes bang when you pull the trigger, then why bother with a Glock?
There's no mechanical device that will ever replace prudent gun handling and you can't spend any amount of money or buy any product that will "make you safe".