re: US: March 2020 experienced 34k fewer deaths than the average March of 2016-2019. 15% drop.

Actually in numerous states automobile related deaths have increased even with less people driving. Generally speaking, speed (on all streets) is the major factor in accidents and related deaths. Less people driving actually means more people driving faster, and a higher change of serious injury in an accident, see Missouri -- Missouri Traffic Deaths Increase Despite COVID-19

In some ways traffic, especially inter-city traffic is good for safety. Its very hard to accidently hit another driver and (or a person or a bicyclist) resulting in a serious injury or death when driving 20 miles/hour. At 40 miles/hour its much easier. And at 80 miles/hour no one is walking away.