Downr@nge, the "trigger safety" feature on most guns is simply a mechanical device that won't allow the main body of the trigger to move to the "bang" position unless engaged.
It is more of a drop safety than a "let you fiddle with the gun and call it 'safe' " safety. In the case of a gun that has no manual safety, a quality holster performs the "no shooty until intended" function nicely.
The big picture question that someone else using the search function might be wondering about is why we call a trigger interlock and a manually engaged lever a "safety". Honestly they are different concepts and calling them both "safeties" is confusing. I generally refer to devices as "manual safeties" or "passive safeties" when the distinction matters.
"Passive" being safeties that will be disengaged by a deliberate firing
Examples; grip safeties, trigger safeties, the features that keeps a gun from firing out of battery, revolver transfer bars, features that prevent a dropped gun from firing.
"Manual" being devices that require active disengagement
Examples; safety levers (of course), holsters, internal keys (not a fan of them, but they qualify), magazine disconnects (also not a fan, and I'd never trust such a device), external locking devices, trigger plugs, or chamber flags
Some guns require manual safety devices more than others, the prime example is a light single action gun such as an M1911 type pistol
Most guns really don't need a manual safety, double-action revolvers or autos will rarely have one, the XD platform has a pretty good grip safety, single-action revolvers rarely cock themselves and can't fire hammer-down (modern) or in any condition but the trigger being pulled.
Don't discount a gun without a safety lever, no hardware device can replace safe gun handling practices and your best safety is keeping your brain engaged and following the 4 rules. Modern guns don't "just go off" even if abused, and a mechanical failure that could cause such an accident would often not be prevented by an external lever.
