The [1] explanation of how they get those IP's kind of shocked me a bit....
How does Luminati acquire its Mobile IPs?... Luminati pays a monthly fee to the application vendor, who passes that value on to the user by not displaying ads.
So essentially it sounds like an app developer installs the SDK into the app and gets paid to provide proxy traffic through the users device... As an alternative to in-app advertising.
This seems highly unethical to route random traffic through people's devices right? Especially people using proxy's to hide their behavior... Sounds like a TOR network to me...
[1] https://luminati.io/proxy-networks/mobile-ips