Air travel and electrical power:
(1) Are easier to add capacity for during times of peak demand
(2) Actually do fail (even though tolled!) when demand exceeds capacity (brown/blackouts for electrical power, cascading delays easily exceeding those for ground traffic when weather knocks down capacity).
On top of that, it isn't as if driving has been anything close to free -- gasoline and associated taxes are immediate costs for every mile driven, and most people know at some level that each mile also has an additional total cost in terms of insurance and impact on maintenance/lifetime of the vehicle.
And people still choose to make it more expensive in the form of higher-end (and often lower MPG) automotive purchases.
If there's a solution to the traffic problem, instead of attempting to make driving particularly more expensive, it probably involves:
(a) make other transportation options more affordable in terms of reach, time, and money
(b) making the housing market more liquid and affordable, so people can more easily choose locations convenient to their living activities