Rigs of Rods doesnt have mechanical damage by default because its prioritizes frame focus on Soft-Body Physics deformation and is limited by development resources. However, some community-made vehicles do simulate mechanical systems using scripts as far as i can tell.
Mechanical damage systems require a lot of engineering time, testing, and consistent modeling across vehicles.
Not something easily maintained without a large team since Rigs of Rods is a community-driven open-source project, meaning features are typically added by volunteers.