he OS X Finder overwrites directories without aggregating files in both source and the destination. For example, when a directory called /Photos is copied to /Directory/Photos, it will delete its the contents of /Directory/Photos rather than merging. That serves as a case study where the user is not sufficiently involved and, consequently, data can be lost. This behaviour must have been inherited from Mac OS 9 as Linux does not have this problem and neither does Windows.
Yesterday I spent hours driving myself mad as I realised I had lost data 4 months ago. No back-ups could resurrect that data. File dialogues must always be verbose as data loss is the most frustrating experience of all.
A KDE “overwrite file” dialogue; click image for full-sized view
Developers must begin to involve users in choices that are made, as the example above suggests. “Easier-to-implement” or “automatic” are usually a bad idea. For the very same reasons, for example, image2.jpg appears after image10.jpg in file managers. That is simply a common ‘bug’ that mushroomed into a norm.