Manhattan is unlike almost all cities in the US. Most people don't own cars, and a lot of people rely on public transportation to get around. Incentivising public transportation and funding that while discouraging car traffic is what the author is talking about.
I lived in Queens for 2 years and worked in Manhattan. You don't need to explain it to me.
I still think whomever wrote that article is high. Congestion pricing is a tax levied against the poor, like parking tickets. Wealthy people simply pay the parking fines because it's more convenient than using parking structures. I've seen this behavior often. Similarly, these systems aren't primarily designed to reduce traffic--they're a way for the rich to create private roadways. Starting at $9, the fees will keep rising until only the very rich can afford to use these roads, effectively privatizing them. Traffic reduction is just a secondary effect, not the main goal...
How anyone is throwing support behind this initiative is fucked up. These are public roads built with public funds and everyone has a right to travel them. If you don't want traffic don't live in a city with a population of 8-9 million other people... It's like saying you hate the ocean and then buying beachfront. Makes no goddamn sense.