If you mean to ask why some people are voting for single loco even though there is a latest technology like Push-Pull is available, then let me tell you that this poll is actually a battle in between Orthodox and Un-orthodox. That said, let's say you have grown up mostly seeing a train being hauled by a single loco at front. So single loco is the Orthodox method (Even used today for nearly 99% passenger trains). Now this poll aims to find out how people react to a change.