[JumpCrisscross]

> a reusable launch vehicle is not needed for a fast launch cadence

You're correct. But ESA isn't developing a mass-manufactured ELV, either. Themis is basically rebuilding Falcon 1, Prometheus a methalox Merlin.

Nothing ESA is doing generates launch independence from America (or China) in respect of LEO constellations or a war in space.

(That said, I think reusable super-heavy launch, e.g. Starship, will render both mass-manufactured ELVs and these Falcon 1/9 siblings obsolete.)