The physics behind rockets requires the structure of the rocket to be extremely light, so structures can’t have more than an absolutely minimal safety factor. A

The physics behind rockets requires the structure of the rocket to be extremely light, so structures can’t have more than an absolutely minimal safety factor. And the will experience extremely high vibration loads and g forces. And almost all the mass of the thing is extremely volatile fuel, which needs to be consumed at fantastically high rates and burned directly next to where it’s stored. Effectively, the margins have to be so small and thus to leave a much higher risk of failure than most other engineering problems, even when done completely correctly.