Depends on the vendor. Some just admin access to the array, other require a two person authorization to delete it.

local admin credentials or two factor or the BEST is a immutable time-lock, so a snapshot cannot be deleted before the retention period that was set when it was taken expires

Pretty sure fire is a risk to servers as well.

So which one is the ground truth if there is a difference between them?

Seems to be rather sturdy in my experience. Would we even be able to read an electronic record after 100 or 200 years of storage? Old piece of paper is quite accessible.

Seems like fires and floods would also affect servers too.

... and an incorrect password policy and poor access control. Usually, in these institutions, if STS is not responsible, there are third-party companies, usually proxies, that are responsible for managing the firewall and accessing the data. The lack of procedures and lack of supervision from the authority, combined with the delay from the service providers, leads to a situation where everyone does backups as they think is best. That's why it takes so long now, because STS restores data from different formats, from different places, made at different times