Does sustainable packaging always cost more?

Per unit, often yes. Per order, not necessarily — because the switch forces the audit most operators never do: rationalising the number of packaging SKUs, right-sizing containers to portions, ending the habit of double-bagging and cutlery-by-default, and renegotiating with fewer suppliers at higher volume per line. Many operations discover the waste was never the material — it was the unmanaged variety.

From Walking Away From Plastic: Serving the Planet — and the P&L — the full reading, with the method behind this answer.