I just conducted a most unscientific student of taxi-drivers talking on cell-phones in New Orleans.
I took 6 cabs; 4 of their drivers couldn't resist the impulse.
One said it was an emergency and I told him he was in luck I was a doctor, how could I help- he then talked to someone in his household about finding the two dishes he'd prepared for dinner and quickly switched to a language I have limited familiarity with.
One said a cabbie had been murdered the night before and they (cabbies) had to stay in touch - to which I expressed doubt how that was a successful preventive measure.
A third insisted he was more distracted by my request that he stop talking than by talking.
I gave up and afterwards would only take cabs where the driver agreed not to answer calls.
Drastic times call for drastic measures.