What the driver is responsible for
The condition of the vehicle is the driver's responsibility, not the owner's or the mechanic's. It is the driver's duty to confirm a vehicle is fit before driving it, and to drive it only after checking.
That responsibility continues on the road: obeying traffic rules, carrying the required documents, not doing what is prohibited, and driving with care for everyone else using it.
It does not end at a collision. A driver involved in an accident must stop, help the injured, inform the police, and stay to be identified. Driving away from an accident is a separate and more serious offence than the accident.