7 – Why do not hook_file_insert () and hook_file_presave () need to clear the cache?

I think all the hooks need the cache to get deleted (or at least I thought so far), but it seems these special hooks do not need the cache to be cleared. I also tried this on a clean Drupal 7 installation.

Does anyone know how this magic happens? I thought the cache could be deleted when files or nodes are saved, but I did not see that.