So, for a country like India, it's possible for the government to ban gambling and restrict citizens access to any gambling site, only those who find their way around the use of VPN can access gambling site..
You are overestimating the Indian government way too much. They are competent, but not that competent. They have banned porn, crypto related stuff etc, but people over there still use them pretty easily and many of them aren't even tech smart.
I have several Indian friends which is how I came to know about all of this stuff.