Snapdeal is just using the opportunity to get more customers into it's ecosystem, it says that it would take 1 rupee (0.015 USD) commission to deliver 2000 rupees (29.495 USD) and that too from the cash received from COD (cash on delivery). People paying online for products on e-commerce sites is all time high in India as they don't have cash to spare, so I don't really see a way it's going to be successful.
As for Paytm, I really doubt their commitment to the security of their products. This was my experience on vulnerability disclosure on their product - https://medium.com/timebender-technologies/paytm-says-to-me-...