There are a lot of stated reasons for the toll, which is supposed to reduce cars on the road and increase revenue for public transportation.
What I find reprehensible is that they did not properly set up an easy to use exemption system for people who are disabled (I applied for my spouse who is disabled and we were told that there is NO timeline for when we can expect his application to be processed). And most NYC subway stations do not have elevators so you might have to go 20 blocks out of your way to actually get down onto the subway platform or back up again.
Secondly, even if you live in the Zone you have to pay to get out. If you make less than $60k per year you can get a 50% tax credit for rides in excess of your first 10 per month. So the minimum that one will pay per month is $90 before any discount is applied.
And Uber and Lyft lobbied so that they are not charged, but their passengers will be.
It is a pure money grab from the people who already pay too much to live in NY (often to be near family).