The point is not to double the amount of work to reduce errors. The point is to record both where money came from and where it went to. This simplifies analysis

The point is not to double the amount of work to reduce errors. The point is to record both where money came from and where it went to. This simplifies analysis, reporting, etc. down the line. The fundamental unit of a double-entry system is the transaction, which records from where things came and to where they went. In software parlance, it's an event-sourced system rather than the stateful/interactive system of single-entry accounting.