Driverless cars simply don't have the mileage yet to prove they are safer than driverful cars. But there's also no indication they are less safe, based on casualty rate so far.
Waymo said that they'd hit 4 million miles back in Nov 2017, they seem like they've done the most miles, there are several other contenders, so I took a wild guess, trying to err on the side of overestimating # of miles.
There is an indication that they're less safe! They have (very conservatively) 5x the number fatalities per mile driven! Now, look, the error bars on that estimate are of course massive. It is plausible that they are much safer and they just rolled the dice and got unlucky. But this is data, as long as you include the error bars.
Driverless cars simply don't have the mileage yet to prove they are safer than driverful cars. But there's also no indication they are less safe, based on casualty rate so far.