It's a billion person country.

It might not make sense for every country to demand things like this, but that doesn't mean it doesn't make sense for giant countries too, and it doesn't make it inefficient.

At India's scale costs are already amortized anyways, but worse, consider India's physical location. It's surrounded by hostile nations (Myanmar, China, Pakistan, make a wall around it). To get data out of the country you're talking about moving it through hostile territory, or moving it through vulnerable subsea cables. Not only is the bandwidth probably more wasteful than the extra compute needed to spin up another set of servers to serve the billion people in India, but the network cannot be relied on to keep working during any sort of crisis.

Luxembourg or whatever demanding all data processing happening internally would be meaningfully different. It's less than a million people to amortize over instead of more than a billion. It's next door to allies which the data could reasonably be stored and processed in, instead of isolated. But we're not talking about whether or not Luxembourg should demand this, we're talking about whether or not India should.

Afaik, Myanmar is not a hostile country. Neither the elected government nor the military dictatorship has animosity at the state level.

China and India are not friends. China needs Myanmar because it would allow it to transfer its goods faster and cheaper: no need to go around through Strait of Malacca.

If pro-China government is installed in Myanmar it means that it automatically becomes hostile to India.

Controlling trade routes explains many wars and coups.

To be honest I know next to nothing about Myanmar<->India relations. Everyone has been suggesting that the new Myanmar government is closely related to China, so I was substituting in the China<->India relations.

Right now yes. However any neighboring country with a recent coup doesn't fill you with confidence.

Data can also move by satellite.

Someone can correct me if I'm wrong, but I don't believe there is meaningful amounts of bandwidth available via satellite today. Even something like starlink today is just a bent pipe from ground station to ground station (and is super recent).

Whatever bandwidth is available would undoubtedly be quickly consumed if the land lines were cut...

Nowhere near enough.

We require businesses to register themselves, to file taxes in every country, etc, etc. We don't have global governments, and supervision of local financial data for fraud/criminal activity should be done locally. It sounds to me like its more efficient compared to the alternative.

If it was wasteful, then there would be no CDNs like Akamai and Cloudflare.

And Netflix would not have data centers in virtually every ISP in the world.

Ohh poor Netflix, the bandwidth costs are so unfair to them!

Mastercard isn't Netflix. The amount of bandwidth is likely orders of magnitude less.