You seem to be under the assumption that allopathic medicine is based on scientific proof. Most of it is not; there is not such thing as "scientific proof" -- the nature of science itself insists that all items can be unproven. Many "scientifically proven safe" drugs are later determined to be dangerous. So much for the "proof" of the safety of modern medicine.
All forms of medicine are based primarily on the trial and error of previous generations of healers. Chiropractic care, like all other forms of medicine, is scientifically studied. However, since you can't take out a patent on it, you won't find pharmeceutical companies lining up to test it.
You also seem to be under the assumption that chiropractors simply hang up a shingle and go into business. On the contrary, they attend medical school and are also licensed medical professionals who yes, frequently practice under peer review.
Dangerous? Compared to 180,000 deaths per year caused by medical malpractice among allopaths?
As for chiropractic care being unsafe for kids, in 31 years of pediatric chiropractic care, there has only been ONE questionable report of injury.