Maybe that's what the customers like. Also, are they getting a free ride as part of the experiment? I'll bet they'd like that, too!
I doubt it is free.
“I liked that we didn’t crash. Oh! I also liked that we didn’t run over and kill any bicyclists.”
That’s what I was thinking. A ride is a ride - as long as it gets you where you’re going without any excitement or delays there’s not much to distinguish one from another. Now, in a test vehicle you’d expect they might be better maintained/monitored etc. As you say, the fact that it was a BMW 5 series, likely new or nearly new, probably has more to do with the high marks than the actual driving from point A to point B. If the test vehicles were 4 year old Hyundais I’d bet the average ratings would be lower even with the exact same self driving tech.