At the 2017 Mexico GP, Niko Hulkenberg was told to exit the car because it wasn't safe. He stood out on the nose of the car and jumped off using a specific protocol.
There's also an indication for corner workers that alerts them to the unsafe condition.
I'm guessing the nose must be grounded and safe to walk on somehow as part of the regulations? I remember watching it live and wondering if every car has a different procedure, or was it just Renault that had the nose. Whereas Ferrari might say, get out on your right side, or stand up in your seat and jump over everything..
The nose is electrically connected to the rest of the car. If the car has a potential difference to ground the driver will already be at the potential of the car. The point is you make sure you're not touching the ground and the car at the same time as that would make you a convenient current path.
There's also an indication for corner workers that alerts them to the unsafe condition.
https://twitter.com/F1/status/924723086875938817