So just a update on this.
A huge amount of traffic is being routed through AirTel (Indian provider) which has been difficult to nail down due to the enormous IP ranges they own and lack of consistent records for identifying them. I have found a way to identify them and I am working to implement it now, unfortunately it's a wide net but we have little option at this point. I am sorry to our Indian users that will be forced through the captcha gate now.
Edit:
If anyone is curious as to what is going on and why this has become such an issue. These bot farms are using proxies via desktop and mobile free addons/games, etc. Often the user has no idea that the "free" app they installed includes this in the agreement for using the product. This allows the bot farms to hide behind thousands of devices, blending their malicious traffic in with the general noise normal activity. There are some apps that even give the user's a kick-back for installing it on their phone, usually with the concept of getting paid for "sharing unused bandwidth". Google has been working to ban products that are acting as a proxy on their app store, but the damage is already done and we are left holding the bag.