Not saying that people don't try, and there is that odd politician who does come only from money. By and large most chief ministers victory can be explained not by money, but more by identity/group based politics.
This is pretty much also exactly the same to what happens in the US.
> How do you buy votes if
> the ballot is secret?
The answer is by distributing 2,000INR notes to people and transporting them to the polling station, relying on reciprocity and promising more to come if you get elected.
People in India will take money if you give it to them, but they will vote on identity only. This is because there is no reciprocity - once the voting is done the politicians have no incentive to pay them again and they don't. The only reciprocity that exists, if at all, is along identity and everyone gets it.
Take a look at any CM in any state of India - their win is largely explained by identity and not money. The current PM who was two time CM of a state, doesnt even have a house to his name.
> People in India will take money
> if you give it to them, but they
> will vote on identity only
> This is because there is no reciprocity
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.