You write “Audi seems more confident about human drivers…” I think it depends on the driving mode and the possible kinds of requests that may issue from that mode. Let’s say the driving mode is “automatic parallel parking” and the request to the driver is “this parking place is to small, find another parking place” and the car is stopped when the request is made. That is clearly a safe level three request for intervention.
In Audi’s case the car is in “traffic jam” mode moving at up to 35MPH and I’m sure the requst for intervention is “You may now resume driving at higher speed.” if the driver fails to respond the car continues at low speed or maybe even stops. This might be almost as safe as the above automatic parking example
There might be a large number of level three modes where a request for human intervention that is ignored or un-noticed by the driver is safe.
I agree with Google that in general, requests for driver intervention are not safe. It would only be safe in special cases, like the one Audi implemented.