not just limited to embedded environments, some docker images used in cloud setups also don't have bash - alpine doesn't have it. The alpine image is used a lot, due to its small size; you can add bash easily, but bash is not part of the base image (there is a difference if you are in an ssh session to a container that doesn't have access to the net)

   docker run --rm -it alpine
   / # bash
   /bin/sh: bash: not found