[tumbling_stone]

Politicians don't dole out cash and go pray that the voters will honor their agreement. They have a way of making sure that their bought votes are delivered to them.

Buying votes happens mostly in slums and other non-affluent areas. These are the places where the concept of privacy hasn't yet formed and everybody knows what everybody else is doing. Also, a politician is not expected to work for them his whole term. It is natural to see your local representative only during the times of election. So politicians have the two key ingredients to enforce an implicit contract. But the biggest weapon these politicians have is intimidation. Since it's not hard to mostly figure out the faction that refused to vote for the money they took, they can be persecuted and intimidated.

Of course there's no official source to cite this. My driver is very chatty and quite insightful about the politics in India.

[Nano2rad]

Vote is secret in India. There is no way for politician to find out where your vote went except some guess work, but still people vote for the politiician who paid the money which is strange. There have been no news report about politicians taking revenge because people did not vote for him. If such news had come election commission would do something and media would not be silent.