The TriPlanar has no A/S scale because Herb Papier understood that different cartridges track differently and that different records act differently. This makes any A/S scale arbitrary and essentially useless.
Still, a scale gives a visual marker that makes it easier to use and easier to return to a setting. Making physical adjustments in tiny increments can benefit from visual reference points. The fact that different cartridges track differently does nothing to reduce the value of knowing relative adjustment position. :-)
Tim