Why do discs in DVD cases get put in the "wrong" way?

I’ve noticed this before but it struck me as being a repeating problem when I was watching the Breaking Bad box set. When I opened the first DVD case I noticed that disc 2 was on the left and disc 1 on the right. So I swapped them over. Eventually I got to the end of disc 2 and opened the next case. And I absentmindedly put the DVD from the left of the opened case in my player expecting it to be disc 3! Nope! I watched the entire episode at the beginning of disc 4… gah!

A friend if mine tells me he did exactly the same thing with a different box set. And I’ve noticed it in several other DVD sets.

So what’s the beef? Is this the industry standard? Is there a reason for this? Or is there a randomness here which I only notice when it’s wrong?

My WAG: The first disc is the one you see first upon opening it, which is the one right behind the cover. For cultures which read and write from left to right, that would be the disc on the right.

Compare it to the title page of a book, which is on the right. To its left is a blank page, or an illustration, or something that is clearly less important than the title page.

Single-disc cases always place it on the right, so it makes sense they would start there.