Concourse by default hides newly created pipelines from the public. That's not in the interest of Open Source projects, which want to show the entire build process.
fly --target ci expose-pipeline --pipeline example
fly --target ci hide-pipeline --pipeline example
A pipeline which is exposed will still not show build logs. For that, every job must be set to "public: true" as well.
Unfortunately it does not seem to be possible to set the exposure in the pipeline definition itself. Therefore the "expose-pipeline" command must be re-executed if the pipeline is destroyed and recreated.