Is it accurate to say that Japanese are just used to orderly boarding in general? I haven't visited yet but just watching the amount of order and efficiency at train stations on YouTube is crazy compared to the US.
In my limited experience from boosting Japan I'd say that Japanese public life is generally much more organized than in the US.
At the train station there are markings indicating were the doors of the train are gonna be and people line up at the markings. It makes it really easy to pick a good spot to wait for the train and makes boarding so much less stressful. At least for me. In SF train stops I'd always be strategizing where to position myself and keep repositioning as more waiting passengers are bunching up in certain areas. I'm crazy that way. So Japan was very relaxing for me.