Here's the reply I received from the BCA about the topic:
Tables always have a head rail (where the nameplate is) and a foot rail (opposite end from the nameplate). No manufacturer, to my knowledge, has ever designated the other rails as left or right. There is usually some type of number system stamped into each rail to designate its position on the table.
In addition, no game of pool has ever been based on using a "left" rail or a "right" rail, so I do not think there was ever an industry standard for what is left and right.
On a casual basis, some table installers mark rails as "left" and "right" for the purpose or reassembling the table quickly. For this purpose, they stand at the namplate, face the table, and the rails on the left are "left" and the rails on the right are "right".
So, I would have to suppose that as long as it's conveyed exactly which rail you are talking about it doesn't really matter how you determine it. Kinda like you in Glen's depiction, take his car on road X and I'll take mine on road Y. As long as we get to the same place it doesn't matter how we got there right?