In Austria, statutory insurance for damage to others is mandatory (liability insurance / Haftpflichtversicherung). However, liability insurance for Ukrainian cars does not automatically cover damage to third parties in Austria. Damage is only covered if you have the green card.
In order to protect Austrian motorists from not receiving compensation in the event of damage to you or your car through no fault of your own, there is a font that covers these damages.
If you are responsible for damage to a third party and/or an object, the Austrian driver will quickly be compensated for the damage, but they will try to get the font back from you at great expense. The Green Card solves this problem and makes the bureaucracy easier in this case.