Replying to all resumes would be the polite thing to do, but often it simply isn't practical. If a company receives 200 responses for an ad, or experiences a continual deluge of unsolicited resumes, it would spend an inordinate amount of time sending acknowledgments. If you really want a receipt for your resume, send a stamped, self-addressed postcard asking for one. If you make it easy, the human resources department will comply.

Successful people begin where failures leave off. Never settle for 'just getting the job done.' Excel!
Tom Hopkins

It is extremely unlikely that anyone coming out of school with a technical degree will go into one area and stay there. Today's students have to look forward to the excitement of probably having three or four careers.
Gordon Moore