"exceed passenger airline levels of safety" - could be a severity/mitigation issue - there are less mitigation options in space, so reduce the severity/frequency of incidents beyond what is economical for airlines?
Airliners* don't tend to end up millions of miles away from somewhere they can make an emergency landing if something goes wrong.
* Except for RyanAir - they seem to land a million miles away from anywhere you may actually want to get to.