> ... it really would be great to find some way to "fix" this edge-case.
I don't think anything needs to be fixed. This is along the same vein as the misguided thinking that `[Z] (3,2)` should yield `(2,3)`. I also think the comparison to [*] is invalid since it operates on number-y things, and [X] explicitly operates on 2 or more lists or iterables. My thinking is that doing `[X] ((3,2),)` is kinda like doing `[X] ((3,2),Empty)`... Not exactly equivalent, but almost. The Cartesian product of singleton sets is again a singleton set (ie. product [[1]; [2]; [3]] is [1; 2; 3] My feeling is that current behavior is fine. At most, perhaps a warning in a similar vein to `sink context` warnings, eg. 'Useless use of meta-reduce [X] on single list' or something
