You're correct that the Netflix catalog is different for each country. However, the shows you're offered are based on your current location as determined by you

You're correct that the Netflix catalog is different for each country. However, the shows you're offered are based on your current location as determined by your IP address, and not according to where you bought the subscription. So the American subscribing to a cheaper Indian plan, would see the US catalog when he logs in from an ISP in the US, thus he would still get the shows he wanted and save money if the Indian plan was cheaper.