Carpet area is the *only* thing that matters

Just got possession of my Sunworld flat in Sector 32 last month, and yaar, things nobody told me! The super area vs carpet area difference was huge. Builder quoted one price but effective sqft rate came out way higher than I calculated earlier. Matlab, they show 1500 sqft but carpet area is barely 900 sqft. It feels like a 'hidden cost' of inflated super area. Did anyone else face this with other Greater Noida builders? Wondering if I could've negotiated better on this. Should have pushed for carpet area pricing, no?