[txg]

If you want to run some time-consuming tests prior to pushing your bug fix it's convenient to run those in your separate worktree. You can continue working on your original branch while the tests run.

[XorNot]

The article starts out by talking about the built in git worktree command which will do this for you, and is built into git already.[1]

The question is, if that exists why are the virtual trees meaningfully different?

[1] https://git-scm.com/docs/git-worktree