Why is it safe to use a gas stove indoors but not a gas grill?

Burning propane and natural gas indoors isn't the problem, its burning it in an area with low ventillation that causes problems. When propane and natural gas burn it produces noxious ges that can make you ill or even kill you if they are not ventilated. Letting your car or lawn mover idle in a garage with the garage doors closed can do the same thing.