The entire comparison is flawed because the surcharges for optional equipment are made by the manufacturer, not the dealer. It is also questionable whether VW uses a full cost accounting for the Passat and takes the surcharge from Passat to Golf out of thin air or even places it below production costs. You make money with the top models, not with the Golf Trendline...
Also compare who contributes the bulk of profits in the VAG group. It is definitely not the core brand VW...
I guess this was a classic "We’re already there, the scaffolding is still up, we’ll just do it quickly and anyway we’ve earned enough with the neighbor" business, hence the 7,000 EUR... I can’t imagine the neighbor had his entire house clad for 7,000 EUR. That would be absurdly cheap. If I take medium-priced material, about 40 EUR, and 150m² of facade, the material alone costs almost 7,000 EUR...