Often (not always) the top bun is the worst offender, but it’s most certainly not just about the buns: if you look closely, the unique characteristic of Japanese McDonalds (separating it both from McDonalds in other countries as well as from other similar chains in Japan) is that in each photo every burger layer (be it bun, meat, lettuce, etc.) is offset by a seemingly-random factor on its X axis.

I’m sure discussions like this is exactly why they did it. Considering other chains in Japan don’t do this, it clearly has nothing with regulations (unless those are really unevenly enforced).