I think some dishwashers are somehow worse performers than others. In the flat I was in before, the landlord installed Ikea dishwasher was terrible (I don't know who was the actual manufacturer). If I'd put a butter knife in there that still had traces of butter going in, they would still be there coming out. Somehow, this even happened when using the 70 ºC program. I even tried using the most expensive pods, for the same result.

In the new flat, equipped with some mid-range Siemens, I don't have this problem anymore. I use the exact same pods, same butter, and same knives. Hell, even the "quick 1h 45º" program gets rid of pretty much everything, even using the cheapest pods.