It's not that hard to not get fired on day one of your job. Even if you are completely ineffectual and incompetent, you can still stick around for years. We have known coworkers who do more harm than good, but since they show up on time, no one seems to mind. And even then, they only showed up on time most days. There are some coworkers we've seen stay on just by strategically walking around the workplace with a wrench in their hands. Again, it is almost a challenge to get fired on the first day. Unless you sleep with your boss's wife. But even then, you might still stay on for like a week before he finds out.
Maybe these folks didn't want the job in the first place or just decided they like stealing more than they liked being employed. For some more employment drama, here are some stupid reasons companies fired people.