I found this question on the internet and I feel curious about it. I assume that even if the direction were to be switched, it would not matter because the people driving from east to west and vice-versa are basically the same as before hence conserving the total angular momentum of the system. Can anybody explain if this actually has any effect?
Imagine following the cars in Britain with your fingers as if seen from above. Regardless of the position or road direction, your fingers would move clockwise. Similarly in the rest of Europe, they will move counter-clockwise. Due to Newton's 3rd law, Britain's cars accelerate the Earth and the rest of Europe decelerates.
Now this has much less effect than if there was any E-W asymmetry and its effect is weakened since only the projection onto the equatorial plane is taken, but it is there. The regions on the equator would not play a role and of course there has to be an asymmetry between left and right driving people between the two hemispheres, since everything in the south hemisphere would be reversed.