What might be relevant is knowing that there is an accepted medical practice that is practiced by all of the three related types of medical treatment providers mentioned in this thread:
Osteopath: provides SMT
Physiotherapist: can provide SMT
Chiropractor: provides SMT
SMT: Spinal Manipulation Therapy
To be registered as a clinical Chiropractor in Australia requires 5-6 years of university education - though this hasn't always been the case. Also, current entry recommendations for A-level in Biology, Chemistry, Physics, Maths haven't also always been the case either. Uni core subjects include anatomy (including cadaver studies)- neurology, biomechanics, etc.
The entry by the royal australian college of gp's page on Osteopath indicates similarities and differences between Osteopaths and Chiropractors:
https://www.racgp.org.au/afp/2014/april/osteopathy/
e: I've no real interest in this topic, but it did motivate me to discover some interesting differences and educate myself on the strengths and breadth of helpful scope of the three providers mentioned above.
Also, it confirmed my suspicions (and experience as a customer), that Chiro is mainly useful for the simpler mechanical mis-alignment (only) problems.
I was surprised to see however that international student training costs (5-6 years uni) for Chiropractic are AUD$180,000 plus.