If you follow Youtubers like Jim Browning that tackle this sort of scam-based cybercrime operations then this will come as absolutely no surprise to you.
AI will make this industry even more successful. Telemarketers read from a script anyway, so it's only a matter of time until these scams are fully automated. We're starting to see some of this already, but it will be fully adopted in a few years.
That said, scam calling is a uniquely large industry in Bihar and West Bengal as neither have a significant tech industry, and see very little foreign investment, so there is less incentive for state politicians to crack down on something that generates easy money. Most BPO and Software outsourcing companies in Kolkata and Patna tend to be the old school Indian outsourcing companies that got priced out of Bangalore/Gurgaon/Hyderabad/Pune because they have low margins, and thus pay lower salaries (around $3-7k a year compared to $20-70k a year in Tier 1 cities or product driven companies)