Ah, OK. This works because you're using single quotes on your strings, meaning the escape sequence `[ is preserved until it reaches the globbing layer. This will not work, for example...

  gi "`[abc`]"

...because the `[ will be processed before the string gets sent to globbing, meaning the back tick will be removed. This would work with double quotes:

  gi "``[abc``]"

...because at the command line level this will evaluate to `[abc`] and the globbing will know that the square brackets are literal. So I will concede and downgrade my complaint from "impossible" to merely "overly complicated for the layman".