Hi ftcat,
I was trying to follow the recommendation of the wiki page on the toll key. If I understand the reasoning in the wiki correctly, then the idea is not to provide hints for avoiding the toll booths but rather to indicate that free circulation between any villages accessible via the toll road and located between the toll gates is possible. If you think that a different approach is more appropriate for the specific situation in Zambia, then it might be a good idea to document the reasons in the wiki.