Yes, but banks tend to have websites with accounts and those accounts need to be deactivated when a customer should no longer have access (or, even more finicky, specific accounts for a client need to be deactivated or activated as they change their usage).

All this essentially forces the use of some sort of soft deletion. (Activation flags are sort of just a more complicated form of soft deletion).

Status (active/inactive/other) and existence (present or deleted) are very different things, they may be separated most of the time. Legal requirements can prevent deletion of inactive data, so in some cases one may have a lot of inactive but must keep data. Soft delete can help in some scenarios, for example you want to give people a way to re-activate accounts, but hide the ones marked as deleted.

not every thing is a transaction though, say a deleted piece of ref data that still has FKs to other stuff etc

These are still versioned in many serious finance systems

Is the same true in mass surveillance?

and the blockchain.

Which is a decentralized, distributed ledger, so... banking! :)

By that definition the tally marks on my beer mat are banking, too.

"banking"