The refueling system is fundamental to the transportation problem. Without refueling you don't have transportation, you have one time deliver and Elon knows that.

That's why he wants to mass-produce Starship.

The idea is to let the first Starships just sit on Mars and serve as part of the first colony.

I'm sorry but that is absolutely, fundamentally and totally wrong. It goes against literally everything anybody from SpaceX including Elon has ever said.

Is it, though? I think you're stuck with the mindset that there's only one type of Starship when there isn't.

There's a distinction to be made between cargo ships, tankers, and crew transport. The first uncrewed cargo flights have zero change of returning to Earth.

There's simply no infrastructure for generating fuel and refuelling yet. So unless you want to tell me that Musk is some sort of space wizard able to conjure methane fuel into the tanks of the first cargo ships that land on Mars, this is exactly what's going to happen.