I thought English is the official language in India? If so, does it mean Indian people speak and write in English fluently (similar to native English speakers)?
India has a three-language formula or language policy. A child in a school anywhere in India, at least as postulated in its language policy, is expected to learn 1) his/her state language, for social integration at the local level; 2) Hindi, for national integration and upward socioeconomic mobility within the country; and 3) English, for global and national communication and upward socioeconomic mobility.
India presents the MOST linguistically diverse and culturally dynamic case to the entire world from prehistoric times to this day. The greatly diverse fabric of Indian linguistic repertoire has offered unique language situations to linguists so much so that there are concepts in linguistics (the filed of studying languages) that are identified with India only: Sprachbund is one such concept.
That said, unfortunately, the hegemony of the ruling elite has continued, and a limited number of people can be considered (according to credible research) actually fluent in English though its middle-class is steadily rising. Because India has the largest human population on earth, its elite and educated middle-class can easily outnumber many countries' populations.
Pakistan can be regarded a mini-version of India because it was once part of India in the recent past. However, there are striking differences between the sociopolitical cultures of both the countries.
So, it is possible for someone to run into an Indian writer who can write fluently; however, as FLW noted above, there may be some visible linguistic deviations that will sound unfamiliar to a person not acquainted with such deviations. This does not just include the native English speakers from the U.S. or U.K., it can also be equally applicable to another ESL context such as Pakistan. Since we do not share many such linguistic deviations with the Indians (though we have our own; much like the U.S. and the U.K. idiosyncrasies and idiolects), reading an Indian writer rings a bell.