No, OS X has Git, that's the equivalent. I actually don't know Free BSD well enough to say for BSD, but for Linux for example I'd say it's Sourcetree or SmartGit.

Your getting hung up on the Tower example, Tower is far from the only example of OS X applications having a smoother UI than nix. I always felt it comes down to a culture issue, nix users don't mind the lack of polished GUIs if there's a command line tool (which you're so continently demonstrating)