Status of a subscriber on a list (
_ListSubscribers) is not the same as the overall status in All Subscribers (
Lists are sub-sets of All Subscribers for which SFMC maintains status. Lists are sendable. Publication Lists are not.
You can be
unsubscribed from a List and still be
active in All Subscribers.
All Subscribers represents every subscriber in the entire Enterprise 2.0 account, not just a single business unit. Business unit membership and subscriber status are maintained in a hidden data view. The
_Subscribers data view does not accurately reflect business unit status or membership. (This has been a frustration for many people working in the platform for a really long time.)
The most accurate business unit membership and status come from a tracking extract that specifies the business unit.