Rather than "Share", read the action as "Send to".
This clarifies the author's preference for icons with the arrows, fits with the usual mix of upload/post-to-social-app/open-in-other-app actions, and removes the motivation for the somewhat out-of-place milkshake icon.
(You can keep the 'share' label for marketing purposes if you want...)
Exactly. Apple does not refer to this icon as the 'share' icon in official documentation. It is actually the 'action' button[1]. As in, I have some data in this app, and I want to do something with it outside of this app. Hence, the symbol of an arrow moving outside of something.
Many of the possible actions resulting from tapping that icon (on iOS) may be unrelated social sharing (e.g., copy, save to photo library, assign to contact, etc.).
This clarifies the author's preference for icons with the arrows, fits with the usual mix of upload/post-to-social-app/open-in-other-app actions, and removes the motivation for the somewhat out-of-place milkshake icon.
(You can keep the 'share' label for marketing purposes if you want...)