Docker-engine is the daemon built by docker. Podman is an opensource work a like. Docker-engine doesn't support running as a user other than root. Podman does. This announcement says minikube will work with Podman running as not root.
I remember hearing that development of docker-engine was ceasing, but could obviously live on as it was forked. I guess rootless is some of the work that Docker (company) wanted to keep proprietary and out of this open-source project.
Really quite a shame, although understandable from a commercial perspective.
Assuming that these improvements are finding their way back into an open-source project, I'm glad to hear about this work from minikube and Podman.
Rootless mode for Docker is completely FLOSS, and its main contributor (me) has even never worked for Docker (company).
https://github.com/moby/moby/blob/master/contrib/dockerd-roo...
Docker engine does.