Don't you need to donate at least $100k to influence senators or influence party positions in the US? Sure, you could "buy" a politician for cheaper, but you're not guaranteeing they will toe your line.
India is ridiculously expensive - bribes often amount to 50 lakh rupees to 1 crore + rupees, which amounts to roughly $50k-100k per politician. Not to mention bribery at the lower rungs of the ladder where everyone from the politician's toilet janitor all the way to the politician's chief of staff will demand their pound of flesh, usually in the tune of tens of lakhs of rupees (~$10k).
That's not a good thing. From what I understand, a lot of "cheaper" bribes in India are for things that the government employees must do as a part of their jobs so like a bribe for these government employees to do their job basically which still filters up to the highest levels of government.
Why would you agree to stick your neck out for something illegal on the cheap when you can wring the ordinary people to do your job?
All this is based on second hand information so please correct me where I am wrong. Also probably things are different in different parts of the country?