With all due respect, that's the best place for a safety.
Glock rocks.
If you pull the trigger, it goes bang. If you don't pull the trigger it doesn't go bang. If you don't want it to go bang, don't pull the trigger.
The Glock, actually, is an excellent cross between single and double action. When the gun is just sitting there, it's ready for a double-action shot. If you fire but release the trigger only about 1/8", it will be ready for a single-action shot with a trigger break exactly like the first double-action shot. If you release the trigger fully, the next shot will be double-action.
I'd wonder if anyone could do the same thing in a pistol with a bobbed hammer (avoiding the Glock patent).