Even the LEMs have the firing pin block, ergo, unless the trigger is pulled and held to the rear the firing pin is locked and cannot be driven forward into the firing pin. That is functionally the same as a drop safety.
There are three safeties, the half cock notch the hammer rests in when decocked (that is why you do not lower the hammer by pulling the trigger, that causes the hammer to be lowered past the half-cock notch), the manual safety, and the firing pin block safety. Of course the LEM normally does not have the manual safety or the half cock notch, but since the hammer goes forward between shots, even if for some reason the sear slipped there would not be enough force for the hammer to drive the firing pin into the primer, plus you still have the firing pin block that would prevent the hammer from driving the firing pin into the primer even if it did have enough force.
There are three safeties, the half cock notch the hammer rests in when decocked (that is why you do not lower the hammer by pulling the trigger, that causes the hammer to be lowered past the half-cock notch), the manual safety, and the firing pin block safety. Of course the LEM normally does not have the manual safety or the half cock notch, but since the hammer goes forward between shots, even if for some reason the sear slipped there would not be enough force for the hammer to drive the firing pin into the primer, plus you still have the firing pin block that would prevent the hammer from driving the firing pin into the primer even if it did have enough force.