“Systematic reviews of controlled clinical studies of treatments used by chiropractors have found no evidence that chiropractic manipulation is effective, with the possible exception of treatment for back pain.[8] A 2011 critical evaluation of 45 systematic reviews concluded that the data included in the study “fail[ed] to demonstrate convincingly that spinal manipulation is an effective intervention for any condition.”[10] Spinal manipulation may be cost-effective for sub-acute or chronic low back pain, but the results for acute low back pain were insufficient.[11] No compelling evidence exists to indicate that maintenance chiropractic care adequately prevents symptoms or diseases.[12]”
It’s because what they’re doing can sometimes provide temporary relief and when it works, it works fast. An underlying cause has made some inflammation, they stretch things out, relieve some pressure in places that shouldn’t have pressure. But they’re not fixing anything, just letting your body get back up to barely functioning until the underlying cause rears it’s head again. Messed up discs are their bread and butter, but they’re just resetting the house of cards you call a back.
Actually fixing the problem is a big, expensive, scary, painful deal and (US) chiros let insurance companies off the hook for a long time.