For instance, a menstrual cup is generally more cost efficient and certainly more environmentally friendly. And it can be manufactured with simple equipment (rubber injection mold).
There's a lot more potential hand-contact with menstrual blood when using a cup than pads, and while someone in the western world might scoff at the idea that using a cup could "ruin" a women's virginity, that could be a real concern for an unmarried girl in rural India.
"Cup manufacturers urge the use of clean water for cleansing. This may not feasible in all countries or conditions, and alternative ways of managing menstrual flow will need to be employed"
Edit: Oh, and as jackityquack mentioned in the sibling comment to this one, that requires running water. I didn't even think it that far, but yeah...that's an even bigger barrier.
And, yes it might be the most cost effective, but if you can't convince a white person to use it, then we shouldn't be telling Indians to use it either. It's an option, but the market should and will decide. (p.s. my roommate uses one too.)