With Google Docs/Office 365 the last time I lost a full document is years ago now.
I am old enough to have stored my laptop in the fridge when writing my PhD thesis, to keep the fault rate down. However, that is when hard drives where still mechanical, and online backups not a common thing.
Until the government gets better at overseeing such large projects, this will keep on happening. However, as governments not spending their own money, but tax payers money instead, there is little incentive.
The reality is that data leakage, incorrect access, etc. are all much more likely with a bespoke in-house product than with google docs, even if they haven’t bothered getting the cert needed.
For that reason I think these bespoke solutions are not going anywhere for the foreseeable.
In regards to the Post Office scandal, that same ballsup could happen in any cloud.
There is also might be functionality that is not part of Google Docs in terms of metadata on notes, who information is searchable etc.