That is correct. At the same time, one can assume that a client also engages with the subject matter and is willing to think along. You cannot put together an offer outside the standards for everyone. Besides, this also results in a loss of comparability.
There is nothing to add to the explanation overall, however, it remains incomprehensible to me that craftsmen are shielded for their "incomprehensible and/or incomplete" offers, while customers (= laypersons) are expected to engage with the topic.
Of course, it is advantageous for a customer to have dealt with the subject matter and to know in advance what to expect. However, in my eyes, precisely such offers distinguish good from bad ones by the fact that some are written in detail and somewhat comprehensible for laypersons, while others are scribbled in "technical jargon" and reduced to the essentials. Just like the motto: "The customer can just ask" or "the customer simply has to read up on it"....!
It would not hurt the offerer at all to directly refer to the mentioned DIN and, if applicable, the calculation condition under the calculated item. That way it would be understandable for the customer, also comparable, and would save the craftsman from "stupid" questions on this point.
I am convinced that especially in this case better comparability would be given and that this would certainly mean an additional plus point for this craftsman compared to others.