It isn't being done behind-the-back of proxy operators.
It's one more revenue stream to be able to remote control real android phones to pass device attestation checks etc.
It's marketed to users with phrases like "earn money from your phone whilst you sleep".
And it's entirely Cloudflare's and Google's fault. When you say you need to have X to do Y, people are going to find ways to get X.
Ok, that makes more sense. Hooray for stuff getting even worse...