Yes the pricing is not for locals. Its for tourists that fly in. Lots of people fly in for Disney in Orlando and Miami for beaches or cruises. Now a tourist can hit both cities without flying again or renting a car.
There are a lot more costs to a car besides gas and tolls that add to the cost of that trip. But even besides that, you get to take 3.5 hours of your life back doing things that you can't do while you're driving.