I don't see how my posting could be misleading. I was responding to your posting about a 'scale' of charges. I would have thought that the type of scale I was referring to was obvious in the context of my overall comments.
The 'conventional view' which you refer to is in fact EU law and the position of the Competition Authority, at least when they were bringing cases in the late 1990s in relation to such activity by certain associations. Breach of competition legislation is also a criminal offence, however silly that may appear to some, especially in regard to criminalisation of abuse of dominance. Indeed, you appear to accept this as the current legal position. I am not aware of any examples where consumer welfare benefits from such activity, but perhaps, you might be able to provide some examples.
The information asymmetry you refer to is also known as moral hazard, where the expert (be it a professional, consultant or tradesman) has knowledge which the client does not have, and can leverage this knowledge for his/her financial gain.
It is my understanding of what you subsequently say is that a scale proposed by an association of profit maximising firms can be a reasonable indicator of costs for the consumer. IMO your argument in favour of fee scales could be applied to any service deemed complicated, and possibly misunderstands the nature and welfare enhancing effect of competitive markets, however imperfect.
IMO the consumer can gauge a knowledge of such costs by looking for a number of quotes and seeking a break-down of these quotes. This break-down will give scope of work covered by quote and, sometimes, hours to complete each activity in that scope. Also, the prospective customer can do such things as ask around from others who have availed of similar services, and get an idea of prices that have been paid in the market place for such services, as indeed is happening in this instance.
The cost of any professional service, IMO, present no greater or lesser challenges for the customer than any other professional service, and does not require the assistance of any price fixing or "benchmark" to help the unfortunate customer.