Yes they do. It is part of their religion to only eat Kosher food. The author wasn't complaining. The author was explaining why they were looking for vegan food.
So far as "traveling," I think, as a group, Jewish people have traveled a lot, e.g. migrated all over the world.
Here is something to think about. If you have no to little sanitation or water for cleaning items (living in a desert), then a Kosher diet is a pretty good way to stay healthy.
When i am in a strange or unfamiliar place, with unknown foods and food sources, eating kosher assures some significant known food hygiene , sanitation, and preparation per Old Testament. As a veterinarian, food hygiene and sanitation are important to me.
My college roommates and Our best man was Jewish. We are Lutheran.