I've wondered whether ekiben would fare well as a food truck in a major North American city (prepared in a commercial kitchen and just distributed by truck / hot-dog stand / whatnot).
Some food trucks around here (Minneapolis) have kind of elaborate hand-cooked processes. You can see confusion where there's a line to order, and a bunch of people standing around for minutes waiting for their order.
https://www.gimletmedia.com/startup/kitchen-confidential-sea...
It's because of 'customization' every American customer seems to want in a resturant here.
Almost no one seems to order food in US as it's offered by the restaurant. Everyone wants something replaced with something else, with something added a little more while something is subtracted a little less.