...a city that big will be crushed by bureaucracy.
Also the maintenance cost will be sky high, not to mention the electricity bill to keep the street lights on, keep some sort of defense against Grimm going. And every single public service will be very difficult to maintain because it is too big and too disorganized or too organized to be functional.
Just public transport alone needs multiple section for each part of the city and a HQ, or else you need to have a giant pile of people to take care of Monthly income alone.
imagine to try to file a complaint in city that big and they tell you to go to the North side of that city and the North side tell you to go to the south side and the south side call you to go to hq. And then the whole sequence starts again, the bureaucracy will be a nightmare of a nightmare.
Unless they're working like the city, which have 25 section for each corporation to manage, it will be a fucking nightmare.