You put many airbags especially on rear row seats. Many passengers at the back also don't bother fasten seatbelt. Without seatbelt buckled up, airbags could cause serious injury and even death without the seatbelts tensioner limiting the passengers movement. Some cars even ferry 4 people behind pushing the side passengers leaning on door panels. Imagine if the side airbags deployed, the force of inflating the airbag is like being hit by a car. Because of this, those who often ferry passengers who don't fasten seat belt only cause more harm than protecting passengers.