Vehicle Parked In Driveway Was Totaled By County Grader During Snowstorm - County Claiming Immunity

Hello Reddit friends,

My uncle had his vehicle totalled by a snow grader in a recent snowstorm. The vehicle was parked in his driveway and when the grader went to turn around, it smashed into the vehicle and drove away.

After submitting a police report, photos and video of the incident (entire situation was recorded), the county sent a letter claiming "government immunity" and not liable for payment as the road grader is not considered "motor vehicle" Is this valid? My uncle does not have full-coverage on the vehicle and his own insurance will not provide any help. His un-insured vehicle claim (recommended to complete by his insurance agent) was denied.

Is there any legal action he can take? Is there a specific type of lawyer he should look into getting? Or, is he out of luck and that's just how these situations end? I find it ridiculous that the vehicle was parked IN HIS DRIVEWAY, totalled, and he is solely responsible for fixing.

A few other relevant details:

• State & County - Clear Creek County, Colorado
• Emails have been exchanged where the county is aware / admits fault, but then proceeded to send the "immunity" letter.

Any advice would be greatly appreciated!