Bookmark Favicons Reset After Cache Clear Or History Clear

I still don't quite understand why Safari does this. I clear the cache often for work related endeavors as well as history. Each time I do this and close Safari or restart my computer, all bookmark favicons are reset. I still don't get why Safari is the only browser that does this. I also use Chrome, Firefox, and IE for work related testing without this issue. Can anyone explain this? Am I missing something?