The EU regulatory environment has also been very different than the US on this subject. NHTSA and the various DMVs have been very laissez-faire about robotaxis, not banning them and allowing some level of (frankly unsafe) testing. The EU has taken a more traditional approach, where public road deployments will require type classification, which necessitates a whole bunch of legislation exist. For L2/L3 vehicles, that only recently came into existence. That framework doesn't exist for L4+ vehicles, so they cannot currently be deployed in Europe regardless of development status.