Photos/Media/Files and Full Network Access Does anything stop an application with Photos/Media/Files and Other ("full network access" and "run at startup") permissions from simply uploading ALL of your photos and videos to some stupid server they control?  

Is it access to store and read their own photos/files, or total access to everything on the phone? Does it matter if it's on an SD card or internal storage?
If an app has access to your data and the Internet, there's actually nothing to keep it from doing such things indeed. But if it did, it probably won't go unnoticed (as it would use bandwidth for that, someone surely would have noticed). Which is one reason one should prefer apps already used by many people, and from a trustworthy source.