I've had friends apply for positions (with amazing, enticing and fun cover letters), and then, after a week or so of hearing nothing following up to ensure that you've received their application only to to continue to hear complete silence.
Sending even a form rejection email takes no time at all, especially if you create a task reminding you to do so. Not responding when someone has put in a large amount of effort to create a tailored resume and unique & fun cover letter is extremely rude.
I switched task manager over this treatment and makes me embarrassed to call myself an Aussie.