I could understand if they were about 16 years old and actually abused by their employer, but generating random numbers to test the locking of phones? Basic maths should tell you that the probability of matching some real phone number is actually quite high.
Moreover, what exactly were they testing? i.e. if they were testing nonexistent numbers, then how would they even know the phones were blocked in the end?
Yeah well, the thing about pressure (of the sort the author has describing) is that you make mistakes - the kind where some times 3+3 = 9.
Source: I queued jobs to nuke the whole production database (relax, we had automated backups+verification so we recovered fast enough; and then added some gating so make this more difficult in the future)
I don't think they're even actually interested in programming and I cannot comprehend why they do it as a job or why they got hired.
I.e., the only thing they were considering was whether the number entered at the start of the test would show up in the right places at the other end of their system. They simply didn't consider that an actual phone would be shut off along the way.