Docker for Mac is a Linux VM with some tools to glue your Mac to that VM. It gives you the illusion that your Mac is running containers, but it's not -- Linux containers are a Linux thing. Some virtualization is going to be necessary unless your host OS is Linux. One could argue that maybe MacOS should somehow run the Linux kernel. Windows tried that as WSLv1 and it didn't work that well; WSLv2 just uses a VM.

The net impact of this is not particularly high. I always write my apps so that they can run on the local machine, and just have my CI system put them in Docker images for deployment. But, that does require some effort, and some language ecosystems or applications make this nearly impossible (relying on details like case-insensitive filenames, OS quirks, etc.)... so people just develop inside a container to work around that. (I would never tolerate it, but it can work OK for things like PHP where your edits take effect in the running container without having to rebuild anything.)

Windows runs containers without a Linux kernel. They made a runC API out of existing Windows APIs.

runV and VMWare Vsphere 7 can run each container in its own VM.

WSL v1 did not run a Linux kernel at all, but v2 does.

Windows runs _Windows_ containers without a Linux kernel.

And even with WSL1, they didn't implement the cgroups APIs, and couldn't support Linux containers.

Here we go... Boot your container host in the browser! https://copy.sh/v86/?profile=archlinux

Wow, that's doing every filesystem operation as a separate fetch to the server? With no caching? Simple to implement, but about as slow as you could possibly get!

Yeah, but it boots up really fast (from a snapshot), and that's the important thing for a demo!