The EU is mostly stringent on the environment, and single-use rockets are pretty bad for the environment: all the metal and sophisticated parts must be produced, only to be thrown into the ocean.
I would expect reusability to be a requirement based on that factor alone. You ca produce carbon-neutral fuel, but there is a lot of environmental load involved in production of the very rockets.
I would expect reusability to be a requirement based on that factor alone. You ca produce carbon-neutral fuel, but there is a lot of environmental load involved in production of the very rockets.