From the Online Etymology Dictionary (emphasis mine)
Travel: late 14c., "to journey," from travailen (1300) "to make a
journey," originally "to toil, labor" (see travail). The semantic
development may have been via the notion of "go on a difficult
journey," but it also may reflect the difficulty of any journey in the
Middle Ages. Replaced Old English faran. Related: Traveled; traveling.
Traveled (adj.) "having made journeys, experienced in travel" is from
early 15c. Traveling salesman is attested from 1885.
Our concept of travel is very modern, and recent. Even in the 19th century when travel by train was possible, still most of the population didn't travel without good reason. The main reason for this was travelling was really expensive. Firstly you'd have to pay to get where you were going, then you'd have to pay for accommodation when you got there.
Travel was only realistically possible for the rich.
Roll back to medieval times, adding to the expense you've danger. If you couldn't pay for armed guards you're at the mercy of everyone you meet on the road. You've to either pay for food and lodging or forage and camp as you go, which effectively halves your daily distance & doubles your travel time. In medieval times it was completely the norm for people to be born, live and die of old age without ever venturing more than 10 or so miles from their home.
Given, in the west, how quickly we can travel from one side of the country to the other, and even travelling to the other side of the world is possible, it does seem unreasonable that people didn't move or travel, but it's only because we're looking through our "affluent western reality filters". If you go to parts of the developing world, you'll find people who "don't travel" and would be slightly bemused at the idea.
Consider, 40 or 50 years ago, lots of people left my country (Ireland) to find work abroad. People who were leaving for America, Canada & Australia were often "Waked" (as in a funeral/celebration of their life). Yes it was a party, but the concept of "wake" was added because it was understood that those people would never return. While parents/siblings would receive letters, their wider family and acquaintances would never see or hear from them again, and it was like they'd "died".
We are incredibly lucky to live in this age of easy travel, it's only been around for 40 or so years. Roll back to the 18th century (introduction of rail travel) and before and try to imagine how difficult it was to get from Warsaw to London, through - for the time - heavily populated areas, over difficult, badly maintained roads, expensive coaches, dangerous sea crossings ... Contrast that with London to San Francisco, weeks long sea voyages, then wagon train across hostile country that could take months.
Also, the books give a better impression of distances travelled and the time spent on the roads and in the wilds. The travellers are knights or travel with guards, and are less worried than most about bandits. They are mostly landed gentry with money or have liege lords to give them travelling expenses.
