Server bans are not public for a few reasons. For one they often contain sensitive information (such as IPs, screenshots and chatlogs that aren't appropriate for everyone to see or even because witnesses wish to remain anonymous for fear of backlash) and for another it's nobody's business except the player being banned why or for what they were banned. That information should be provided to the banned player, and anyone who wants more details about their ban should seek out the banned player, not the staff.