How does "mixed" work? Variations at the local level? People just ignoring the rules and doing what they like? Or is this a joke that I'm too American to get?
Also, I can definitely tell those colors apart for left and mixed super easy, I totally know which ones are which, just don't ask me to prove it.
I assume the traffic just moved slow enough at that point in time that the rule was "make way" when you saw another vehicle rather than "always stick to this particular side".
Again, this is just an educated guess and have absolutely nothing to back up my assumptions.
I think the question is asking for an explanation of how that is possible that some areas are right and some are left within the same country. Does the local government decide (city, state, etc), or is it something else, and why.
Additionally, they seem to be partially color blind, since they can't differentiate the purple from blue.
Edit:
Copying my other comment here, based on some light Internet research which may or may not be accurate.