"saving expensive lawyers from spending their time wading through the documents."
Do lawyers want to lose that much time in billable hours? I'd imagine part of what lawyers like is making lots of money and this will be a limiter.
Their options are to lose that much time in billable hours, or to lose all their billable hours because the client found a law firm that doesn't bill so many hours for grunt work.
Yes, the lawyer bills by the hour. But, a good lawyer will have enough work either way - so they may as well automate the easy stuff, take a reduced rate for that, and still have a full-plate of interesting work at their full hourly rate.