Now, to be fair, there are Indians that speak perfect American English. My dentist is one of them. Graduated from Utah Dental School, etc. Furthermore, the problem is not "Indian Centric." There are a bunch of other ethnicities that are willing to take lower paying phone support jobs but can't speak English with a reasonable American accent (or put sentences together, accordingly). You'll encounter that when you call a company with a customer service center on the West Coast (CA, AZ, NM, NV etc.). There could also be Foreign customer service centers in East Asian countries (eg. Phillipines) that have the same problem.
Supply, Demand, and Economics. These are the people taking these customer service jobs for the pay being offered... not US Native speakers. This, and the companies willing to cut costs and employ them, thinking that as long as they can speak English, it will work out. But it doesn't. And they only way they will learn this is by "feedback" from the callers. We have to be able to understand each other. It works both ways.