Are painting costs very high or normal?

We have foregone the fleece and had the paint applied directly onto the plaster. For our taste, this is completely sufficient and still looks great. We saved 5000 EUR (for a 140 sqm bungalow) as a result.

We had a similar offer in 2020 from our general contractor (so with a small markup), from 14,000 - for 152m2, 1.5 stories, very similar to yours. Also regarding the scope of services.

It was also too expensive for us. In the end, we hired a painter ourselves. He did everything for 6,000, including materials - however, in consultation with us, he mostly skipped sanding/puttying and only did the rough work. Instead of fleece, we used a textured fleece fiber so that not every unevenness is visible.
It saved us 8,000 euros - but to claim that it is not visible would be a lie.

Besides price, one should always evaluate the quality offered and what compromise one is willing to live with.

110 m2 bungalow in 2020 completely plasterboarded with Fermacell walls and ceilings by the general contractor, then by the local painter: filling, sanding, priming for Q3, then Sto smooth fleece and painted with Sto-Color something and walls and ceilings painted white. Additionally, in 4 rooms individual walls (20 m2) were painted in color with Sto-Color. Also, screed filling, sealing joints with resin, sanding and glued with adhesive vinyl, plus skirting boards all complete for ~16,000€ in March 2020. However, rural area and therefore probably no metropolitan (price) surcharge for Munich, Cologne, Hamburg or Berlin whatever.