The people who aren't driving as much is the large group of well-connected assholes who have been abusing the city's parking placard program for decades.
You'd sort of have to live in NYC and observe it first hand to know this, since for curious "reasons" (like the existence of NYP plates) the NYC media doesn't cover it this way either, but it's true.
The other group not driving as much is the people who are semi-indifferent to driving versus transit but the money tips them one way instead of the other. Which is tons of people.
I think your explanation makes the most sense. getting the slack out of the system and reducing corruption plus driving some marginally middleclass to opt for commuter rail because $50/week puts them under.
For many commuters, though, it would suck if you're used to driving in but now have to take the LIRR (and xfer at Jamaica or whatever) or now drive to the PATH station and take the commuter rail in.
You'd sort of have to live in NYC and observe it first hand to know this, since for curious "reasons" (like the existence of NYP plates) the NYC media doesn't cover it this way either, but it's true.
The other group not driving as much is the people who are semi-indifferent to driving versus transit but the money tips them one way instead of the other. Which is tons of people.