Developing a reusable launch vehicle is not needed for a fast launch cadence. The expendable Soyuz family has had 2006 launches since 1957 [1]. That's one in just over 12 days, and in reality, the cadence has been a lot faster at times (for long, continuous stretches).
JumpCrisscross|5 months ago
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.)