Why doesn't the image auto-download even though it is enabled in the WhatsApp settings?

Why doesn't the image auto-download even though it is enabled in the WhatsApp settings?

In the user scenario, the image will not be auto-downloaded when the sender is not in their address book and they have not sent a message to this sender before.
In the enterprise scenario, a business should use Message Templates when first engaging a user to establish "trust"; in doing so, the WhatsApp Business API Client will then abide by the in-app auto-download setting.