How do you propose people find out the cost of traveling if the pricing is dynamic? People won’t check beforehand, and they’ll already be in their cars when they find out the cost

How do people find out how much traffic congestion there will be for an upcoming drive when they need to be at their destination at a specific time?

Induction, typically.

guess, and many people are frequently late.

Google Maps

Navigation/maps providers like Google/Apple maps, etc, will incorporate price estimates as well as time estimates- they can even show multiple options if there are price-time tradeoffs available.

This exists already and generally they post prices both online, and on digital signage well before the entrance ramp.