us-east-1 and us-west-2 pricing is locked to each other. Typically the power differences are related to the cost of power and transit/peering, not the capital of building the facilities.
Northern Virginia and Oregon have (generally) cheap power and cheap connectivity to anywhere in the world, with plenty of peering opportunities. In a developing country or with more expensive infrastructure (Mumbai, Tokyo) costs will be higher to get power and pull in fiber to peering locations with enough capacity to supply a provider of Amazon's size.
This is the correct analysis. Power costs are high in India and its often unreliable, requiring many industries to have expensive generators in place as backup.
Northern Virginia and Oregon have (generally) cheap power and cheap connectivity to anywhere in the world, with plenty of peering opportunities. In a developing country or with more expensive infrastructure (Mumbai, Tokyo) costs will be higher to get power and pull in fiber to peering locations with enough capacity to supply a provider of Amazon's size.