Shared inventory exists for corporations. However, corporation hangars are rarely used by regular corporation members, especially in larger corporations. Corporate hangars are managed by roles and generally serve the purpose of storing and managing corporation assets.
Sharing assets between individual players can only be done through corporation hangars if the corporation is small enough and if anyone in the corporation have the roles to access corporation hangars. On the other hand, sharing assets between alts, especially those that are in different corporations, is not implemented.
We already have a similar system for the bookmarks, where a bookmark folder can be shared between players based on an access list, regardless of whether characters are in the same corporation or not.
Already existing Admin, Manager and Member roles in access lists can be used to determine who can perform different actions with items in the shared location.