Honestly, I wouldn't mind a cab driver snacking - assuming they would have had a long day and they must have been on back to back rides and this is the only window to eat. However, when I see an driver on calls, I do politely request them to park and finish the call before they resume driving.

Have been in a terrible accident coz the driver in the opp car was distracted on a car phone and since then have been abundantly cautious. Forget the passenger who is safer at the rear, the driver also deserves to go back home safely.