I constantly get questions on why there is no share button on posts I have published. I don't have control over that. Yet I am asked, "Could I please put a share button on this post?" No, that is your choice, not mine.
I post what I do to an audience of friends only. I do not post for the public. I only want those who I choose to see it as friends to be able to read it. It's my privacy setting.
When I post for the public it becomes part of my public on line reputation. Google me and you will see public posts I have made. People make judgements of me based on that. I'm not interested in everyone coming into my world and seeing what I write or think about. It's like as my friend I invite you into my home and we visit casually versus I am on a TV reality show and the world looks at what we are saying.
So when I choose to post something, you are my friend I want you to see it. I DON'T want the world to see it. IF on the other hand you are PUBLIC in your postings, you don't care if the whole world sees what you write or say or think, and you want to share my private friends only post, there will NOT be a share button. If you did share what I posted with attribution to me, you just violated my intentions. You made public something I wanted just between us friends.
Of course copying and reposting without attribution is fine. Just don't mention my name. PLEASE. I won't do that to you either.
SO in other words, If you are public privacy setting, you can't share friends only posts.
I would suggest if you want to share more, set your privacy to a more narrow audience. Friends can post friends posts but public can't share friends.
I hope that helps. If this is too complicated, I won't try to explain it again. GOOD LUCK AND BE CAREFUL OUT THERE. Don't share or give attribution to people who don't want it.. LIKE ME!!!