Can't speak for the data, but can speak as a user of autopilot. I've probably put ~20k miles on autopilot, 5k of those miles on highways.

I think the biggest benefit, safety wise, is it gives the ability to put less mental focus in staying in the lane, and gives me the ability to spend more time focusing on my surroundings. Its easier for me to focus on keeping up with the traffic behind me (like if a car has creeped up into my blind spot) and any potential traffic that is about to cross my path (like a possible red light running coming in hot). In heavy traffic, its super helpful; the auto cruise control is very human-like and will build a gap when someone cuts you off instead of suddenly making one with a slam on the brakes.

There are AP users who prefer to use their time checking on that text message. Those people don't help the statistics / human gene pool.