[BoorishBears]

You'll always be able to imagine cases where a broad toll doesn't perfectly align with a narrow goal, why even waste energy listing them out?

Instead consider how you get the toll to actually do something: in the case of a congestion charge it's by making driving in Manhattan expensive enough to reduce how much it happens for as many people as possible.

Regardless of the corner cases you can imagine, there are more people who drive an M4 that would be unaffected by a $20 charge rate than there are people who drive an 430i. So increase the cost for the people with M4 and you've made your toll strictly more effective... even if there are people who can afford M4s and chose to drive a 430i.

[wcarron]

One could also just make the base rate $150/day and then you'll definitely make it untenable for as many people as possible, which is apparently the goal. This leads to an outcome which is you think is an unfair distribution. But luxuries are necessarily for those who can afford them.

The 'cost' of the action is the same. A vehicle in the city is a vehicle is a vehicle and therefore the toll should be flat, unless that type of vehicle in particular causes more damage to roads or empirically worsens outcomes like traffic or pollution relative to other types of vehicle. Charging people more because they are wealthier is unfairly discriminatory.

[BoorishBears]

Their goal isn't to make it impossible, it's to reduce it. They want you to really need to drive, not just do it because it's convenient.

It seems you might not familiar the actual toll to start, it carves out a lot of special cases for that reason: people with certain incomes are exempt if they already live in the area, ride-shares have special rules, they excluded corridors around the edges of the city, etc.

You're also confused on cost here. It's not cost to the city they're trying to change with a toll (that'd be nonsensical) it's cost to the driver. If cost is hard for you to follow, think of it as "attractiveness".

They want driving to be unattractive, not impossible, not untenable... just unattractive.