Fair point. The season chips under the glass only show rain, not the toll. The summer rate shows up in two places: the opening hint says a passage pays over three times as much in summer, and every cargo card prints the toll it pays today, so the price on the card jumps when summer starts. You are right that in spring the cards still show spring prices, so a first timer can set the line low before ever seeing the summer number. A toll mark on the SUM chip would fix that, and we have added it to the game's fix list.