There’s a world of a difference between refusing to hand over data you have to the authorities, and plausibly not having stored them in the first place.

By end-to-end encrypting messages, but uploading backups to Google Drive and iCloud, and in a non-end-to-end encrypted way by default, WhatsApp (and iMessage, which does largely the same) have quite cleverly maneuvered themselves out of that potential source of legal problems without cutting off law enforcement access entirely.