Wear parts (tires, brakes, belts...) are also part of maintenance because these parts will almost certainly have to be replaced sooner or later. (Washing is not included, by the way, that falls under hobby!)
And even with SF30 you have to stretch quite a bit to get below the (deliberately set low by me) €100 per month. Anyone who keeps honest records (Spritmonitor) will not disagree with me, I think.
An average compact car, driven an average distance, costs €500 per month (buying, owning, driving). You can’t argue with that. That is half as much as the credit many here pay per month and should therefore urgently (and honestly) be included in the calculation.