Taking a car on track carries an inherent risk. Assuming neither party had cover, I would say they chose to take that risk. Each driver should foot their own costs. It's sad, and an expensive lesson to both parties. Crashes on track can and do happen. No point crying over lack of cover after it's gone wrong. This is a big reason why I drive an older cheap car for throwing round a circuit.

Gutted for both the owners though must be heart breaking seeing your car like that.