So you think the congestion fee should be means-tested (or, more accurately, affluence-tested)?
How might such a system work? Have the DMVs from the metro area (NY, NJ, CT) link registered vehicle owners with their taxable income last year and share this info with MTA to adjudicate fees? I think that makes it too complex. You could achieve a similar equitable outcome by making the fee universal and using the revenue to improve alternative transit services (and/or lower fares) that are used more by lower income households.