The construction sums as a basis are, however, unsuitable: The efforts/services of the architect should serve as the basis.
The efforts are taken into account in the levels of difficulty: standard is simple, exposed brickwork is somewhat more demanding, further on with slope location up to pile foundation in sandy soil. Fortunately, all this is only in a handful of levels, not as complex as a tax table. But case-by-case fairness was never the goal of the fee structure – after all, you should only need an architect for the building planning and not again one for the "construction site" fee determination.
The idea of using the basic scale of construction costs is at least far more appropriate than square meters, as these would not reflect the equipment. It is true that buildings become more complex to plan not only due to more expensive materials – nevertheless, the fee structure is not simply a cunning accomplice of greed.
That the HOAI no longer fits as it stands today is due to changes that were unforeseeable or not considered during its "construction." On the one hand, it originates from times when single-family houses were conceptually rather low-tech compared to today; and a "bracket creep" due to boom-driven overheated price increases was not taken into account.
The question I keep asking myself: Is this now a free market or how do such fluctuations come about?
The market is as free as the market participants are used to dealing with each other; the fee structure, on the other hand, is not agile enough to keep up. The consequence is a clustering of fees agreed on divergently and questioning the fee structure in terms of its timeliness.
The condition that emerges from this development is approximately as follows:
The client )
sees himself (in my opinion "spoiled by price comparison engines") as an "informed consumer." He thinks along, and as we almost read here daily in the forum, finds it normal not to come to the architect empty-handed but at least with a preliminary floor plan – i.e., from his point of view, the architect practically only has half the work left;
The architect )
faces this demand market and his fee is subject to a need to justify itself and tries to carry it into the next round in the price spiral game;
The professional liability insurance )
sees it as damaging to the "insured community" to undermine the fee level, while its performance risk, to put it kindly, rather does not decrease – alone: keyword "indemnifier."
A triangle in which basically everyone is right, or at least has a legitimate – even if not congruent with the others – standpoint.