Why does S3 bucket ARN not contain AWS account number?

Question

Unlike other AWS services, s3 resources, ARN does not contain AWS account number.
Few sample ARNs are:

• -- Elastic Beanstalk application version --
  arn:aws:elasticbeanstalk:us-east-1:123456789012:environment/My App/MyEnvironment

• -- IAM user name --
  arn:aws:iam::123456789012:user/David

• -- Amazon RDS instance used for tagging --
  arn:aws:rds:eu-west-1:123456789012:db:mysql-db

On the other hand s3 bucket ARN looks like:

• arn:aws:s3:::my_corporate_bucket/exampleobject.png

Answer 1

S3 Bucket ARNs do not require an account number or region since bucket names are unique across all accounts/regions.