What happens with an online job application?

Assuming I am applying to Mcdonald's or Wal-Mart, does the application go to the corporate office and get filed away, or does the store manager actually see it? I have applied to countless restaurants, department stores, and miscellaneous (supposedly) open jobs, but I have never received a response. Is it a waste of time to try to apply to these places online (which is usually the only option) and, if so - how does anyone ever get hired?