Thanks for the A2A.. This is something that I always thought about when I saw this image, and finally, this question made me do some research..
First, this image is not from India. Not even from any of the other test-playing nations. This image appears to be that of Sultan Qaboos Grand Mosque in Oman:
Even I thought that this may be from some place in India, but after a bit of search, I landed on this blog: Twitter Cricket Sign-In Page, and after closely comparing the architecture of the mosque and the background hills in the two images, I am almost sure that the building in the Twitter homepage image is this mosque in Oman.
Yes, it would have been definitely surprising if Twitter, being a US-based company, used this as their only homepage background. I tried different browsers and tried reloading the homepage multiple times after deleting cookies. As it turns out, this is only one of at least three images that Twitter uses as its homepage background.
Here are the three images that I could find currently being used as Twitter homepage background:
So, Twitter backgrounds have three distinct themes: nature, modern life/city and people (or maybe countryside, first world country, third world country). Any way you look at it, the combination appears more representative of the diverse Twitter population than just a group of young Cricketers!
I think even this combination does not represent Twitter well; I would expect a theme of conversation or human interaction. But perhaps, most of Twitter’s frequent users are perpetually logged in to Twitter on their mobile/web, and hence, Twitter does not care too much about the homepage images that are shown to users only before logging-in or after logging out.