Sure, I was more thinking of hand tuning a photo (retouch, cover up, remove a person in the background). But even if you just tweak contrast and brightness a GU

Sure, I was more thinking of hand tuning a photo (retouch, cover up, remove a person in the background). But even if you just tweak contrast and brightness a GUI probably still wins if you don't know the exact values you want to apply beforehand. But batch processing on its own is another great example where CLI shines. With GUI apps you have to rely on the app shipping that feature, and then it's almost guaranteed it works slightly different in every app, has different semantics, hidden in a different spot etc. On the command line, the batch processing is external to the tool doing the processing, constructed using features of the shell, so once you understood how to batch process with one utility, you can do it with everything.