The mechanic sold the truck because he thought it had been abandoned. That’s a legal definition with legal timeframes and it’s all spelled out in local municipal code. If a vehicle has been parked for X amount of time, and no contact has come from the owner, the person who owns or rents the property upon which it’s parked is allowed (and sometimes required) to declare that vehicle abandoned and either sell it or have it towed away for scrap.
We’ve had that happen three times in my adult life for various reasons. Time #1 was when we parked my little Honda on the street at my then FIL’s house in suburban Denver while my then DH was deployed with the Navy. It didn’t run at the time and we had hopes to restore it. But we were out of state and the X amount of time for that particular city had come and gone, and one day my FIL got a notice from the city that either he had to have it removed or the city would tow it at his expense. So he did. That was our lesson that a car can’t simply be parked on a city street indefinitely.
Time #2 was when I was living in Billings MT and someone abandoned their car out front of my house. It either died on the street and happened to roll to a stop there, or they parked it and couldn’t get it going again. At which point they walked away and never came back. We contacted the police who said that after X days (I think it was 30 days) we had the right to have it towed, and after 60 days we HAD to have it towed. So we did.
Time #3 was when we bought our current farmland. The tenants here had a number of old vehicles parked on the property for restoration which was never completed. They had six months to remove the vehicles and removed two of them, but left a third. After a period of time, I don’t remember how long, the sheriff told us the truck was by definition abandoned and was ours to do with as we saw fit.
So this isn’t a case of a mean mechanic. He may have been required to get rid of that truck, and Althea simply didn’t know. Hopefully not a really expensive lesson, but one that we should all keep in mind.