why is the RIGHT ALT key ignored?

[jidanni@jidanni.org]

Why in emacs, iceweasel, etc. is RIGHT ALT ignored? LEFT ALT is
processed as ALT, but RIGHT ALT is treated like I didn't press it.

xev shows that indeed my keyboard is not broken,
KeyPress event, serial 33, synthetic NO, window 0x1a00001,
    root 0x119, subw 0x0, time 5852895, (169,-14), root:(173,546),
    state 0x0, keycode 108 (keysym 0xfe03, ISO_Level3_Shift), same_screen YES,
    XKeysymToKeycode returns keycode: 92
    XLookupString gives 0 bytes:
    XmbLookupString gives 0 bytes:
    XFilterEvent returns: False

So why if both keys are labeled ALT, why is only the left one processed?
What if you treated SHIFT that way?

Wait, even on the console outside of x-windows it's that way! What's
going on?

There, I logged in to an empty vanilla account on the console and it's
that way still.