Some drivers left Melbourne before fans and media even knew that the Australian Grand Prix had been canceled.

After a McLaren team member tested positive for coronavirus on Thursday, most insiders assumed that cancelation of the season opening Australian Grand Prix was the only possible solution. However, if the decision was made quickly, it took several hours to filter down to the media and fans.
“The problem was that they didn’t do anything for too long,” Ecclestone, at his coffee farm in Brazil, told European media outlet Auto Bild when asked about F1’s actions.
“It’s always down to the one who officially canceled it in the end,” Ecclestone said. “Whoever it is has to take responsibility, also financially. Apparently nobody wanted to do that.”
According to Autoweek’s Joe Saward, the question of who calls off the race is important, as insurance will only be paid out if the state government makes the move rather than the FIA or F1.
Source: Autoweek

