You're right, it's shitty of them to not provide that out of the box. However, if it's such a big problem for you, as others have pointed out, it's easy to solve. If you are paying $500/month for S3, you must be processing quite a large amount of data - as another poster pointed out, there's an easy to fix it. If you weren't going to use S3 for this, what would you use instead for this use-case?