Backup security: Why same keys to backup and restore?

All crypto prodcuts use symmetric keys to encrypt data. RSA operations are so slow in practice that no sane person ever use them to ecnrypt/decrypt data. All RSA based encryption schemes use a symmetric key to encrypt the data and encrypt the symmetric key with the RSA key. The addition of an RSA operation allows to digitally sign the data and/or to safely exchange the symmetric key with a remote site.

For the typical backup restore scenario there is absolutely 0 (zero) benefit from using RSA operations (more correctly: I don't see any benefit). More precisely, there is no need sign the backup with a private key for authentication purposes, and there is no need to encrypt the encryption key with a public key for key transport/exchange purposes. Using RSA keys would simply add complexity and operational risks but would offer no additional benefits.

The only RSA key usage for a backup/restore scenario I can think of right now is if a hardware module is involved (ie. the backup operator must enter the smart-badge into the reader to open the backup file).