It's not even just alternative therapies; we just aren't very good at dealing with lower back pain yet in general, even with scientific medicine.
This is in part why so many alternative therapies claim to help with lower back pain; it's one of those lingering, non-specific problems that real science can't presently do much about. If and when we find a pill that cures back pain, I'm quite sure a lot of these alternative modalities will be significantly; they're preying on desperate people who have a problem the scientific establishment cannot currently help them with much.
We actually are. Stepping away from acupuncture and about myself for a minute so bear with me. Its just that many of the methods are lumped in with quackery or they don't look at everything as a whole. Basically everyone claims relief but its more involved than that. For example I can defeat that pain, I really can, but typically to even get to that point in terms of pain involves former injuries, recent or distant past, or bad habits that need fixing.
Let's take your example, low back pain and let's say its because of constant computer use and not other injuries. In this case, what usually happens is the low back pain is what you feel but its far more complex. The posture is not only bad in the lower back, but in the neck and shoulders too. All the muscles affected are squishing the nerves hence the pain and they never let go, they are pretty much permanently contracted. Migraines, neck pain, stiff arms, all kinds of stuff. After years of use, the muscles lock in this position. Your low back is most rounded, but so is your upper back, your head and neck are forward, and your shoulders are slumped and rounded forward. Your rib area muscles are tight, your pelvis is tilted, and your butt is getting strained as well. Its a whole chain and all the muscles need to be addressed. And one session will not do it.
Furthermore, the persons diet is usually poor, leading to lethargy and more poor posture and lack of strength.
Even AFTER those are corrected and accounted for, the person usually has to restrengthen those muscles for healthy energy and correct posture.
And even IF you're lucky enough to get a client who is motivated to do all of this, which is pretty rare, (because its often disheartening to hear how much they have to change about their habits, and how much is involved for full correction), it even goes one step further. They have to take breaks and CONTINUE to be smart about their posture and health.
And unfortunately, I'm not qualified to give diagnoses, all I'm allowed to say legally is that it might help to look at diet, strength training with proper form, breaks, and stress relief. All I'm allowed to do really is try to fix the pain but its so much more involved than that.
Edit: and that's not even getting into other things. Did you know that emotional stress can also cause pain? Muscles tense up when you're stressed, and if you're a stressed out regularly type of person, it will have the same effect as muscle overuse and bad posture and injuries. This is all VERY well known, but the problem is everybody's and expert... but no one wants to put ALL these things together.
I WILL give massive credit to some of the better physical therapists out there. Some really DO see the whole picture and don't throw pills at the problem, and actually refer out everywhere and see that their patient gets a full picture and full relief if they work at it. I don't know where they're graduating from, but they're out there.
Edit 2: I can talk a lot more about this including chiropractic and how they all fit, or don't fit, together depending on the case, and the severity of it. Everyones different, but the basic components click and make sense when you get the whole picture.