I work as a medical transcriptionist for a physician. I notice there are many people who come in with back pain who have no injury, accident, or trauma. How is it possible to get back pain without doing anything to yourself?
You ask a very good question and one that many scientists are studying daily. It's true that most low back problems occur out of the blue during daily activities. They aren't the result of a sports injury or trauma of any kind.

One thing research has shown: people with other chronic pain problems (nonspinal) are more likely to develop back pain than healthy adults. About 60 to 70 per cent of chronic back pain patients fall into this category. Individuals with mental health disorders, including depression are at increased risk for back pain without precipitating trauma or known cause.

Psychologic and emotional stress along with job dissatisfaction are more likely the real issues underlying low back pain (LBP). Personal characteristics play a greater factor in the development of chronic LBP. For example, studies show that even when trauma is involved (such as a fall or car accident), chronic LBP is more likely to develop in adults who blame others for the accident.

The study of LBP is a complex, multifactorial problem. Your observations match what many studies have shown all along.