Luxury in an airship is quite relative: weight gets you, and something as simple as water or people to handle service, for instance, is heavy. Not a billionaire's dream — not when Page already has a shower in his 747.
Source: my brother started a business for airships and asked me to add numbers to different options. Accidentally, I was also working for Paradox when City Skylines came out, and I suggested adding airships to the game when they asked for new transport methods. No idea if that’s how they ended up there, but happy they are.