There are a ton of different discount options - large customers typically get between 50-60% discount based on committed spending, and AWS is pretty flexible around how that commit lands (they will allow roll overs even if they say they won't). Reserved instances get you ~70% discounts - similar to the committed spending. And my favorite - if it works for you - spot instances on EC2 come at as high as 90% off.
Nobody at commercial volume pays list to AWS - everyone gets a discount.
You can sometimes get a committed use discount within certain regions. Not as extreme as the EC2 discount, since S3 storage costs are honestly pretty low when you use storage classes correctly.
Nobody at commercial volume pays list to AWS - everyone gets a discount.