Well, at least in Bangalore, it's all because of unplanned urbanization. Being the Silicon Valley of India has it's own costs. All the major IT companies set up hubs in Bangalore, resulting in engineers migrating from all across the country to Bangalore.
The traffic has become insane because they're planning to "reduce" traffic by constructing metro trains. Now the thing with Indian govt. system is that nothing finishes on time.
Recently the government tried to "make things right" by organizing a demolition drive in order to save the lakes in Bangalore (or at least, what remains of these lakes). They did this by planning to demolish every single building that was constructed from land encroached from lakes. Now here's where citizens suffered. They paid a huge amount of money to construct these houses in lands that were approved by the government officials or buy a constructed house from builders that had land approved for construction. Ideally, these spots shouldn't have been allowed for construction. But thanks to the amount of corruption in the government, the govt. officials took bribe and turned a blind eye. Now normal citizens suffer because all their lifetime investment- their houses , are now going to be knocked down by the govt. for no fault of theirs!
Things are crazy. On a related note- According To Scientists, Bengaluru Will Be A Dead City In The Next 5 Years