So I tried a bit and for me the Toll Outposts are broken.
- If you place one next to a market: 0 return but 1 ticket cost
- If you place one 1 tile more than the radius away: full return
- If you place the next one nearer than radius + 3 tiles: reduced return
- If you place 5 with half the radius: 0 return and all 5 tickets are gone
I think this was made to not abuse the restart trade feature. But it gets tricky with placing towers if you want them for defence or if the traderoute is not straigt.
Quick fix: Make a toggle ####### for collect toll at the outpost (so you are not ruining the return with outposts you need for defence (like next to the market or some gold pit)
Better fix: Traders have a gold/food budget, which they drop off instead of tickets and the limit is the amount/second they drop off.