Why are some people symptomatic with herniated discs and some are just fine? (especially of the lower back)

Position-room. : The lumbar spine has no spinal, & lots of room. So if a disk protrudes centrally & is not Hugh the nerve roots just move around it. If it's more laterally it can catch the nerve root near or in the foramen where it is not able 2 move & them leg symptoms R common.

Location dependent: Herniated discs can be small or large, and impinge on different areas. Symptoms are likely dependent on the amount that the disc herniation compresses the nerve. The most important factor regarding disc herniations is that research has shown 90% of patients are symptomatically better in one year.