Who offers a car cheaper? BMW, where the things roll off the production line every minute, or a manufactory that creates the car completely individually for you, including the bodywork?
When the plumber buys a few heaters from the architect, he gets a completely different price than when Town & Country requests 50 times the quantity.
And, very important. You have to accept (or want) the house from Town & Country or any other general contractor as it is stated in the catalog. As soon as you have special/redesign requests, especially ones that affect the structural engineering, it becomes absurdly expensive there. Depending on the general contractor, it can also happen that you have to specify electrical outlets already during the planning meeting and pay 150 EUR for each additional outlet. Fortunately, we didn’t have that with Town & Country; except for the windows, we settled extra costs directly with the local craftsmen...
By the way, mostly the same craftsmen who also showed up at the architect’s house across the street...
But with what you write: no 60x60 tiles, no roller shutters, no heat pump... then the 3,000 EUR/m² for the house (without the architect, although in my opinion the architect should be included in the house price, his services are not incidental costs?) is completely overpriced. However, it will probably be difficult to find a 180m² bungalow with the general contractor where you leave 60m² in shell construction initially. That means planning effort, which makes it expensive again.
With the 74,000 EUR fee, the architect is probably still within limits. You can calculate 10-15% of the construction costs. An architect-designed house is luxury after all. It always was and always will be.