karma vs buttons curiosities (e.g. not working delete button)

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On ROS Answers we experience curiosities with the edit/close/flag/.. buttons for questions and answers, but not for every user. Examples:

• delete buttons visible but neither justified nor working (karma to low)
• flag button not visible
• edit button on other's wiki posts not visible (back in January; I myself see one now)

For reference the related question on ROS Answers and related comments on ROS Answers.

Is this a general issue or related to site configuration?