Apple showed it on stage at WWDC, along with Debian ARM running inside a VM. It's coming, if for no other reason than developers inside Apple need it when writing infrastructure software. (Honestly, I'm surprised that Docker didn't get the same pre-release hardware Parallels did)

Because M1 has virtualization and emulation support, unlike the A12Z (not M1) ARM processor on which the docker issue was opened. This is explained here: https://news.ycombinator.com/item?id=25073010

And Docker has the motivation and means to patch and build the M1 Arm version.

You can take it directly from the Docker people:

> Thanks. We're working closely on this with Apple. This is expected right now (and indeed there's nothing we can do about it yet) as the new chips don't have virtualisation support yet.

https://github.com/docker/for-mac/issues/4733

Notice the lack of panic or any mention of "it'll never be done", even implied.

Because Docker has a large financial incentive to get it working?