That's the way it looks until you actually try to make a commercial piece of software by doing that.
As it mentions in the blog post I come from a background of low level system programming (data recovery, even some kernel extensions, etc). It would have not added significant time to have rolled my own file copy tool. Irrespectively, it took about 1000 hours of work to make that app, as it says in the blog post. Things are nowhere as easy as they look. Doing the actual file copy is the easy part.
Let's suppose you had a fancy GUI wrapper around rsync which covered all the command line options, and a tiny output parser to display progress information. What more effort is needed to get a commercial, market-ready piece of software?
I just answered this in another response (and in addition the answer, you could answer a lot of the questions yourself by actually trying the app. It has animations built into it for example, it's clear at a glance that it's far beyond what you described):
It's also not just a GUI. There is loads of code in there that does stuff. For example:
• Scheduling for scheduled backups
• A background daemon that looks for events to launch the UI for scheduled backups
• Manipulation of disks ownership stuff in order to allow backups with permissions to happen correctly
• Volume blessing, etc, in order to make bootable volumes
• Trash handling & maintenance for deleted files
• Deleting files (for removing old backups)
And that was just off the top of my head. The app is many thousands of lines of code and it performs literally hundreds of functions. They're nearly all transparent to the user, and that is the idea.
I used to think like that, turns out things get out of hand quickly once it has to be used by non technical users. I also build a backup app, but in my case for virtual machines [0]
As feelix says it is easy to burn 1000 hours on it. In addition to what feelix says you need to write help, build a site, do a lot of testing, write an installer etc.
It does not compare at all to writing a script for technical users.
I highly recommend the essay "The Programming Systems Product" from the collection "The Mythical Man-Month" which provides an answer to this exact question.
It's also not just a GUI. There is loads of code in there that does stuff. For example:
• Scheduling for scheduled backups
• A background daemon that looks for events to launch the UI for scheduled backups
• Manipulation of disks ownership stuff in order to allow backups with permissions to happen correctly
• Volume blessing, etc, in order to make bootable volumes
• Trash handling & maintenance for deleted files
• Deleting files (for removing old backups)
And that was just off the top of my head. The app is many thousands of lines of code and it performs literally hundreds of functions. They're nearly all transparent to the user, and that is the idea.
