Here's a CNC lathe:
This will produce handles very cheaply to a high consistent standard.
This is the old fashioned lathe used to produce New Forest Brushes handles:
Each handle is individually made using hand tools to shape. Turning handles to a consistently high standard is a skilled job and it's labour intensive and the main reason why these hand made brushes will be more expensive to make compared with those made on automated lathes.
So when you see references to lathe turned handles - it's only part of the story.