If it's so easy to clone it, where are the clones?

I've been reading about Airbus' reusable/recoverable SpaceX-killers for over a decade now. They've yet to have anything to show for their work.

https://en.wikipedia.org/wiki/Adeline_(rocket_stage)

https://www.bbc.com/news/science-environment-33006056 ("Airbus unveils 'Adeline' re-usable rocket concept" (2015))

- "...Airbus says it has been working on the concept since 2010 and has even flight-tested small demonstrators..."

(That BBC article predates the first Falcon rocket landing).