Why do our toll roads not tell us the toll until we have to pay it?

Most other places I’ve seen toll roads there are signs that tell you what the toll is before the last chance to exit without using the toll road. Why do 520 and the 99 tunnel both not tell you the toll until you’re in a place where you have to pay it? Might as well just not tell us since by the time we find out we don’t have a choice anymore