[rdiddly]

Every trip has a cost. It's a transaction. If it costs me $1,000,000 to get to the park (and it's fairly likely I won't make $1M at said park), I will maximize utility by not taking the trip.

In addition, every trip by you, has various costs to everyone else, namely the traffic congestion we're talking about here, plus many other things we're not talking about like pollution, publicly-subsidized police/EMT/fire for cleaning up your car wrecks, etc. Transport modes that allow you to take up less space on the roads per person, or that use separate parallel networks, or that don't pollute or involve wrecks, cost everyone less on these particular axes.