Well that's the magic of the court system, the filing of the lawsuit is to either get them to settle/admit wrongdoing or to force this to discovery.
>I'm even surprised that these trucks have mechanical odometers.
Freightliner vans aren't fancy hi-tech vehicles, they are utility vehicles.
But there's no difference between mechanical and digital odometers here. If you swap a digital cluster, you end up swapping the odometer reading. Architecturally vehicles have seldom moved on from storing the reading in the cluster.
It really becomes a question of where do you store the reading? A engine computer is more likely to be replaced due to an accident than the odometer in the car even though on many vehicles it will still track the mileage.
>they are all digital, rarely fail and (I assume) would be harder to tamper with.
Actually, in most cars they are absolutely tamperable over CAN or physical access. If I remember right, the Honda digital cluster even up to my 2021 just has a standard SPI flash chip that you can tamper with to change the odometer value.