In Italy
I tell you what happen in Italy
With Alitalia, Alitalia Express, Airone, Meridiana, Eurofly, AirAlps, pilots can travel free without any ID tickets (only showing Airline budge and italian Crew Member certificate) because there is an agreement between these airlines.
For any other airline employers, flight crew members or ground staff, they need ID tickets. They can also be accepted in the cabin jump seat (only in cabin) if captain accept to do so.
If there is not agreement, there is not travel insurance.
Ciao
Stef