No excuse. Either flick the safety off with your left thumb, or get an ambi safety installed.
Being a lefty myself, safety and slide release are easy. It's the mag release I have trouble with!
Single actions like 1911, I carry cocked and locked.
Double action only, no need for a safety.
da/sa like my SIG 229, I generally decock so 1st pull is da.
I don't like external safeties except on something like a 1911.