I used to order the same sandwich at the Subway in Toronto (turkey-breast on a six inch, honey oat bread with lettuce, tomatoes, onions, and black olives). Subway opened a store recently in my campus in Seoul. 

I ordered the same meat and the same bread. Then, I said to a server the same vegetables, “lettuce, tomatoes, onions, and black olives.” She added cucumbers and peppers. I asked her why. She answered “I pull out the vegetables customers say.”

I noticed that most customers said nothing about vegetables. They considered the five vegetables on the window as the opt out, default options. Only few customers said “everything but…”

For the people who do not usually make a series of choices for a single meal, opt out default vegetables may relieve their burden. I expect choosing from meats and breads to vegetables and dressings are demanding for most Asians. For them, choosing which vegetables to add are additionally demanding. When they skip choosing vegetables, they may enjoy meals more even though they do not like to eat more vegetables.

Scheibehenne, B., Greifeneder, R., & Todd, P. M. (2010). Can There Ever Be Too Many Options? A Meta-Analytic Review of Choice Overload. Journal of Consumer Research, 37(3), 409–425.

The choice overload hypothesis states that an increase in the number of options to choose from may lead to adverse consequences such as a decrease in the motivation to choose or the satisfaction with the finally chosen option. A number of studies found strong instances of choice overload in the lab and in the field, but others found no such effects or found that more choices may instead facilitate choice and increase satisfaction. In a meta-analysis of 63 conditions from 50 published and unpublished experiments (N = 5,036), we found a mean effect size of virtually zero but considerable variance between studies. While further analyses indicated several potentially important preconditions for choice overload, no sufficient conditions could be identified. However, some idiosyncratic moderators proposed in single studies may still explain when and why choice overload reliably occurs; we review these studies and identify possible directions for future research.