why is there no standard unified UI front-end for version control systems?

on the level of functionality at which I have dealt with version control, it seemed like basic operations I could do were the same on various systems. So, wouldn’t it make sense to have a single convenient and easy-to-learn user interface that could serve as front-end for all popular version control systems, at least for those features that are sufficiently common between them? So let’s say if system X does not have feature F common to 10 other popular systems, an attempt to invoke F on the front-end would bring up “sorry, the current backend does not support this”. And if you need to use something specific to the backend that is not covered by front-end, you could just use its native interface.

I am aware of existence of plugins in Visual Studio, Eclipse etc that seek to achieve this sort of unification within the context of the app. So if we have these plugins but we do not have a standalone “version control studio” type of application that could be used regardless of IDE, is that because it would not work well? Or because the marginal benefit from such additional interface abstraction is deemed to be low, at least for experienced users?

People use GUIs for version control systems?

Differences between version control systems are sufficiently dangerous that abstracting them in this manner would not be prudent. Differences between Svn and Git come to mind.

Edit: Also, abstracting something like Git with a GUI is not terribly useful to begin with.

How would the maker of a version control system make more money by doing this?

They wouldn’t, which probably answers your question about why it doesn’t exist.
For example, this would make it easier for unhappy customers to switch to another company’s product.

Of course they do. For the same reason they use gui versions of file browsers etc. It is often nice to have windows panes open showing, directory structures, file history etc. The one I use has changes the file icons showing if you have the latest copy, if the file is being edited/locked etc. A good gui is very helpful. Sure you can get all this info via the command line but a gui is easier.

that suggests a cunning plan - let a company that makes what they consider to be latest and greatest version control make this front-end and push for maximal adoption. Then use the opened channel of communication your customers to try convince them switch to your system. Or maybe just keep using your front-end with premium features for a license fee.

TortoiseSVN is a GUI that’s also available for CVS, Git, and I think several other version control systems.

I don’t use it so I’m not sure how consistent it is across the different systems.