Despite the large number of people who suffer back pain from disc problems, we still don’t have a clear answer on what treatment is best. Research does support exactly what you pointed out. The main reason to have surgery is that people who have the operation report pain relief sooner than later.
There are still so many variables that it’s difficult to compare treatment results. For example, discectomy (removing the disc) is a standard operation. But even among patients of one single surgeon, there can be differences in how the operation is done. Differences in surgical technique and results can occur from surgeon to surgeon across the U.S., too.
The wait time between onset of symptoms and surgery varies. Some patients suffer painful symptoms much longer than others. Several studies have shown that longer duration of symptoms is linked with poorer results after surgery.
Likewise, nonsurgical treatment varies. Even if all the patients are given the same nonoperative program, some do it, some don’t. Some do it some of the time. Some do it everyday. Compliance (or noncompliance) most likely makes a difference. And even if everyone is given the same program and does it everyday, the way people do their exercises might be different enough to make a difference.
Scientists haven’t given up trying to sort this out. Studies are ongoing to compare different types of treatment and the results obtained.