I don't see this catching more than a tiny percentage of them. What would be the point in leaving a cellphone connected to the explosives while you were workin

I don't see this catching more than a tiny percentage of them. What would be the point in leaving a cellphone connected to the explosives while you were working on it? Even without specific safety precautions, it seems unlikely that most would do this -- it would take extra effort to be vulnerable to this tactic.