First, I got this idea while ago when I moved to the UK from France, I was struggling to find someone to review and correct my CV to match the county culture and the market.

And to answer your question, most (ones I came across) of proofing services are done by software and the result is not good enough to have a confidence to send my CV to apply for job, my idea would use human to do so. This is why I think having some sort of reward will good so people can commit to it.