I have to agree with most of your points Eli
I grow a little weary discussing third party accreditation, because frankly no one in the industry wants to bite the bullet and push for a uniform system, like for instance, the Gas Safe Register as a loose example. Frankly HMG don't want to know either.
It will probably take a few fire deaths where negligence on behalf of a contractor or risk assessor was proven to be the route cause to push HMG to implement compulsory registration or accreditation.
Until then responsible persons are left with very little assistance or advice on how to employ a competent engineer, risk assessor, consultant etc, which is a bit of a joke really. Yet I bet we are happy to prosecute the RP when things go belly up at the hands of an incompetent person having ccontrol employed by the RP .
We like making life difficult for ourselves in this country.