Inspiration did come from The Narrow Corridor[1], which has a good history of the building of state capacity in Europe, and how it affected trade. In particular, cost falls, which is one way “attacked and/or killed by bandits” could be proxied. Another thing that drives down cost is reducing the number of tolls along the road, as discussed in this paper:

https://mason.gmu.edu/~mkoyama2/About_files/StateCapacitySur...

So again, while I don’t think that it’s a stretch to assume traders who had to cross dangerous territories accounted for the dangers, I don’t have a direct source. :-)

[1] https://www.penguinrandomhouse.com/books/555400/the-narrow-c...