The floor of my gas oven has holes along the two sides. When I turn on the oven, I can see the flames through the holes. I've never had a gas stove vented to the outside and never died of CO poisoning. My three CO detectors have never signaled a warning either.
It would be an interesting experiment to cook the identical dish in both a gas and electric oven and see if anyone could detect the difference. I remain convinced you could not.
"If you want to make an apple pie from scratch, you must first create the universe." -Carl Sagan