Any number of things can go wrong when a vehicle is being designed or manufactured. Some common causes for auto recalls are hazards such as:
Fire Hazards
Leaky and misplaced fuel tanks, faulty wiring, and other defects can pose a fire hazard and result in auto recalls.
Seatbelt Defects
Seatbelts can latch improperly or easily become unlatched while a vehicle is in motion. In the event of a faulty seatbelt or seatbelt latch, a vehicle can be recalled.
Power Steering / Crash Risk
Sudden loss of electric power steering poses a serious accident risk to drivers. Somewhat recently, GM recalled 81,000 vehicles for this very defect.
Brake Defects
Faulty brake pads, brake fluid, and other brake components can fail and pose a serious accident risk to drivers.