dash is shipped as a replacement for the Bourne shell, not bash. Thus Ubuntu does also ship bash too. Alpine doesn't have bash installed. It alsonpretty common

dash is shipped as a replacement for the Bourne shell, not bash. Thus Ubuntu does also ship bash too. Alpine doesn't have bash installed. It alsonpretty common not to have bash as part of the base image on non-Linux systems too. You've already mentioned macOS but the same is true for many of the BSDs.