1. Create an organization e.g. testorg
2. Create a user e.g. testuser1
3. Make testuser1 a member of testorg and assign Organization Owner role to him
4. Create another user e.g. testuser2
5. Make testuser2 a member of testorg
6. Log in and out with both users so their public and private pages get created
7. Log in with testuser1 and navigate to testuser2's public pages, e.g. http://localhost:8080/web/testuser2/home
Result: You can edit the page, add/remove/modify portlets, etc.
8. Navigate to testuser2's private pages, e.g. http://localhost:8080/user/testuser2/home
Result: Not only you can see the page, but you can also edit it, add/remove/modify portlets, etc.
The same issue does not exist for Site Owner and Site Member relations.