There are always exceptions to any rule, but the vast majority of Manhattan drivers aren't poor and the vast majority of poor people passing through Manhattan don't drive.
You're thinking of some other kind of place like the middle of america, where that would make sense.
This is not an everyday occurrence except for some occupations. If it happens once a month, it amortizes out to not much. When I lived there, this is when you got a cab, and the surcharge there will be $2.50, for something you do once in a while. Wow, what a scandal /s
In an occupation where you have to drive in lower Manhattan daily, everyone else in your industry also has the extra $15 now too, so you're not really at any competitive disadvantage. And for some of those occupations, the time savings from lower traffic due to the surcharge might actually really be helpful.
You're thinking of some other kind of place like the middle of america, where that would make sense.