But if the closed-source models can do this without the additional effort, that's a significant gap, no?

The point is that the price gap is so much larger than the capability gap, that even with the extra compute needed to make up for the lack of capability, you can still come out ahead in terms of amortized $/work done.

Is it really when they are hundreds of times more expensive?

That is the 3-6 month sota-open gap people talk about, a time-window that continues to move as new models are released on both sides.

See that's the thing, they can't. Every model needs hand holding and guidance.