AFAIK, there is zero regulatory capture associated with realtor associations. They have no special priviledge under the law, and are not required for real estate transactions.
The one thing they do have is control over access to the MLS, plus social inertia.
People should not be surprised we have realtors when we have companies like turbotax raking in millions for 3 pages of boilerplate tax return form fills. You could tell people all day how they can do it themselves yet they will still gladly pay for someone or a service to hand hold them because thats what they really want. Not the ability to do something but to feel fussed over and to minimally think.
The one thing they do have is control over access to the MLS, plus social inertia.