You can encrypt them at rest, but data that lies encrypted and is never touched, is useless data. You need to decrypt them as well. Also, plenty of incompetent devops around, and writing a decryption toolchain can be difficult.
And are we forgetting that they can literally have a multi cloud backup setup in their own country as well or incentivize companies to build their datacenters there in partnership with them of sorts with a multi cloud setup as I said earlier?
Tools like Kopia, Borg and Restic handle this and also include deduplication and other advanced features.
Really no excuse for large orgs or even small businesses and somewhat tech literate public.