Note that the hardware the big cloud providers use for tape archives is very different from the devices the GP poster appears to have used, and usually have robust verification systems.

In addition the need for cloud providers to comply with userdata erasure means they have to frequently test their ability to read and write their backups - which should increase your confidence in their correctness. Yes problems can and do still happen, but IME far less often than the more traditional tape setups GP describes.

Erasure can be done much more efficiently with crypto erasure, where you encrypt the user data and just delete the key when users request deletion. This way you don't need to spend expensive tape vault / library time rewriting a tape.