Mumbai and Delhi comparisons are pointless. They get whatever funds they ask from the center. At the same time for cities like Bangalore, they have to work with leftovers.
People complain the pace of Metro construction is low. But for the money these people get, its already nothing short of a miracle that they are even building this much.
The question isn't Mumbai vs Delhi. It is how costly is tunneling.
And I'm just pointing out that in India we are tunneling at around 10-15 million dollars per mile, far cheaper than what Elon musk thinks it costs (1 billion per mile), and what he plans to achieve (100 million dollars per mile). Essentially, the breakdown is complex and different for different geology, labor prices, tunnel sizes etc. Musk's salesmanship of selling byte sized numbers without context is stupid.
People complain the pace of Metro construction is low. But for the money these people get, its already nothing short of a miracle that they are even building this much.