Whenever I see "problematic" it's always someone who is pointing out something that is not actually a real problem, ie. supported by data or facts, but they desperately want it to be because it doesnt make them "feel" right or it seems like the "right thing to do". More often than not it runs counter to their initial goals (increasing exclusion in the name of inclusion, hurting everyone in the name of punishing the top few, etc).

...No one is being excluded when a service is being underutilized and a small group of people pay extra to reach optimal capacity. There is no way for them to fill this small extra space without flooding it (ie, hybrid only, or Dulles airport cars as they already tried was obviously too much traffic), so why not use it to capacity and earn the city more money from these wealthy people?

Would you rather the government make less money from the wealthy?

Do you really think the small group of people willing to pay $40 is going to slow down the existing traffic?

Would you rather no one uses it, even though the highway can support a small amount of other cars, just for some abstract satisfaction at 'hurting' wealthy people?