Amazon Fulffilment Associate interview questions

Mass group interview, if you got the interview, you got the job. Everyone who was chosen to be interviewed was given a time and date to be at their interviewing location. Everyone was assigned to a group, which went in together (about 30 people at once) and were given a few presentations and given speeches then given a drug test on the spot. Once the drug test results and background checks are completed (takes about a month to a month and a half) you are given an orientation date and time, and paid for it, with it considered your official start date, however depending on your orientation and first day of work, you may start the very next day, or a week from the orientation

After filling out the application ,taking an assessment test , and taking a drug test , they called me to a group orientation and after being there for 7 hours , they tell me that someone else used my social security number at another Amazon location and that they couldn't even hire me . How come they couldn't tell me that when I first applied , instead of wasting my time ? I had to sit through 7 hours of orientation for them to tell me that . Really?