>why the knowhow that European companies like ASML have can't be used to build these foundries

chip production is not simply buying off the shelf equipment and magically you can get to 10nm max yield that is profitable.

equipment is one part of the whole production process. ASML may know how to build EUV but their skillset is not running the fab. if all you need is equipment, why Intel is struggling with 10nm for so long?

Fabs are expensive, and there was little to no interest (as such, no investment) in them. They're "interested" in it now, we'll see how much money they can pour into it.

Unlike the green initiatives funding (try and get that as a startup hah), money going straight to multibillion euro companies might not be a bad thing in this case.

As several siblings have said, this is mainly about willingness/opportunity to invest. Many technical universities have their own fabs for research (I know of DIMES in Delft, IMEC in Gent/Leuven, NanoPhab in Eindhoven), so the capability is there, just not the scale.

I would guess there's a lot more know-how necessary to building an efficient fab than just the photolithography machines.

I don't think there is a good reason other than the willingness to invest in the area has not been there until now.

Chip making was outsourced to Asia because it's cheaper to make them there.