If they don't take Amex then Amex needs to get off their butt and protest it, cite the city supporting monopolies antitrust and all that unless they take Amex. If that argument made the banks buckle then I dont see why they cant do the same thing with city parking
It will be interesting to see whether the parking meters will accept American Express and Discover. In this age I believe they will be required due to the antitrust reasons you mentioned. However most DMV and other government services are still only accepting Visa and MasterCard. I predict they too will begin accepting the others.
Sweet another way for earning miles I hope they'll take amex
But getting 1% or 2% in rewards won't be worth it if the parking rates are 50% to 100% more.